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BE184114.book - Brüel & Kjær

1. 16 00 10 For example To set up a simple box a b c d Select Total Surface Type Box 2 Set Surface Height and Surface Width for each surface select the surface using the Selected Surface parameter For Front set Surface Height 1 2 m and set Surface Width 1 5 m For Left set Surface Width 1 6 m Surface Height for Left is equal to Surface Width for Front All surface dimensions are set now Settings for Front is equal to settings for Back Left is equal to Right and Top Surface Width is equal to Front Surface Width and Top Surface Height is equal to Left Surface Width 30 Sound Intensity Software BZ 7233 User Manual Fig 3 24 Left Result gt Select Total tab and select Number instead of List in the status panel to get an overview of the box Right Hypothetical box surrounding a noise surface 6 Close the Result display select the Spectrum tab and select Front in the status panel According to ISO 9614 2 each segment must be scanned twice and the second scan must be orthogonal to the first Each scan must have a duration of at least 20 seconds 7 Position the probe in one of the corners of the segment Place the probe on the measurement plane with the axis oriented normal to the surface Let the curved part of the probe point towards the plane such that the acoustical centre of the probe the middle of the spacer not the tip of the probe is bisected by the plane 8 P
2. Compass Compass view is selected with the SJ Task selector on the right side of the Template bar The Compass Display is used for on line source location The data displayed in the Compass display can be either Intensity ZF or Intensity AF The display comprises a Bar Graph showing the instantaneous intensity A or Z and a probe with a loudspeaker positioned to indicate the location of the sound source When the speaker is in front of the probe the noise source is in front of the probe and the direction of the sound intensity is defined as positive indicated in Fig 4 10 Left with the white bar graph and the sign behind the dB in the readout When the speaker is behind the probe the noise source is behind and the direction of the sound intensity is defined as negative indicated in Fig 4 10 Right with a coloured bar graph and a sign behind the dB in the readout Fig 4 10 Left Compass display positive Right Compass display negative CHAPTER 4 Measuring ND INTENSITY d ae Intens AF lt SODH2 gt 41 4de tens AF KI 30 10 so The selected frequency or the A or Z total follows the cursor position in the Spectrum display Change the frequency by tapping on the lt or gt icons or the frequency parameter in the bar graph The range and full scale of the bar graph follows the Y axis on the Spectrum and can only be changed by changing the Y axis in the spectrum The direction of the probe c
3. If the result was unsatisfactory press or and remeasure the segment 10 Pressing Q automatically selects the next segment in the series for measurement Repeat steps 6 through 8 for the remainder of the measurement 11 Tap Result gt and select the Spectrum tab and set the Spectrum Parameters to Power A and Tot Pwr A If the A total reading in Tot Pwr A does not have a smiley there are no warnings for the calculated A total However if it has a smiley you must investigate the segment spectra or surface spectra in more detail CHAPTER 3 Setting up the Analyzer 35 Fig 3 31 Spectrum Result tab with parameters set to Power A and Tot Pwr A 50 e tilili mon yill 63 250 1 25 k 4 12 Examine the saved data in the segments looking for smileys in different frequencies or with A or Z weighting 13 Tap Spectrum and use the display cursor to examine different frequencies for different segments and exclude or include bands to pinpoint problems If a yellow smiley is present below a frequency band tap in the spectrum to select this band with the cursor then tap the smiley at the cursor readout to determine the cause If the dynamic capability is too low examine the p I index of the individual segments Select Dynamic C and p I index and step through the segments using lt or BJ in order to locate segments that need to be remeasured NOTE In Fig 3 21 the Tot PwrA has no smiley whic
4. 500 Hz 53 5 dB 500 Hz 41 6 dB a 4 4 Fig 4 9 Sound Intensity Software BZ 7233 User Manual Aural Feedback The hand held sound intensity system provides aural feedback via headphones for guidance and information The aural feedback is an internally generated sound signal generated to aid in pacing the measurement To turn aural feedback on off or adjust for volume 1 Tap Ej 2 Navigate to Setup gt Headphones then Aural Feedback can be toggled to Off or On Aural Feedback Gain can be adjusted louder or quieter by entering the desired value Aural Feedback setup Input Standard Bandwidth Measurement Control Signal Recording Aural Feedback Aural Feedback Gai 17 45 09 Aural feedback assists concentration on the probe and scanning process while still keeping track of Type 2270 s status The sound scheme functions as a metronome or beatbox that beeps at one second intervals during the measurement Every fifth beat is an octave higher After 20 seconds the entire 5 second pattern shifts an octave An alarm signal is triggered if an overload occurs The alarm signal has priority over the aural feedback sequence When Type 2270 is used for noise source location compass mode the metronome signal is still available but is now used for indicating whether the noise source is in front of or behind the probe CHAPTER 4 Measuring 53 4 5 Validation There are Quality Indi
5. 9 Single value parameter Refer to section 4 2 5 for details 10 Single value parameter corresponding result Refer to section 4 2 5 for details 11 Single value parameter corresponding result Refer to section 4 2 5 for details 12 Single value parameter corresponding result Refer to section 4 2 5 for details 13 Frequency band information This area provides visual cues to the state of the individual bands Xs indicate excluded bands smileys are quality indicators 14 Main bar graph A bar graph of the data stipulated in item item 4 according to the selected segment item 18 and frequency indicated by the spectrum frequency cursor item 5 For Pressure spectra the bars in the graph are normally very light on a dark background dependant on chosen color scheme For Intensity spectra the bands with positive direction are also light on a dark background however bands with negative direction are shown as colored bars 15 Reference bar graph A bar graph of the data stipulated in item 3 according to the selected segment item 18 and frequency indicated by the spectrum frequency cursor item 5 16 Frequency Stipulated by the spectrum frequency cursor item 5 17 dB level dB level based on the measurement parameter items 2 and 3 the selected segment item 18 and frequency indicated by the spectrum frequency cursor item 5 Readouts for values with a direction have a or behind the dB to indicate the direction o
6. Determines whether the input is taken from the top socket or the Input sockets at the connector panel Range Low Range High Range Select either Low Range or High Range for the input channels AN NOTE Press the Manual Event key to Autorange the setting High Range will select a range with 0 dB gain which allows the highest possible input Low Range will select a range with 30 dB gain Low levels If you select High Range but the peak level is more than 60 dB below max input then a Low Level warning is indicated in the status panel line 2 Spacer 6 to 200 mm Set the spacer between the microphones as required The 12mm spacer is recommended for 1 2 microphones Transd Used Ch 1 One of the transducers defined in the transducer database Determines which transducer is currently connected to the Hand held Analyzer and once selected the hardware of the analyzer will be automatically set up to fit the transducer You should select a Part 1 microphone from a Microphone Pair This parameter is part of the instrument setup and is common to all setups It can also be set from the Transducers option of the Main Menu Sound Intensity Software BZ 7233 User Manual Windscreen None Select Windscreen Correction if you Correction Ch 1 UA 1070 have mounted a windscreen on the Sound Intensity Probe Transd Used Ch 2 One of the Determi
7. averaged vector quantity rate of energy flow per unit area And as it is time averaged it allows for cases where energy is travelling back and forth and cancelling itself out i e if there is no net energy flow there can be no net intensity however in this case there will be a reactive intensity which is described in section 6 4 3 Why Measure Sound Intensity One application is workplace noise control On the factory floor sound pressure measurements can determine if the workers risk hearing damage and if the noise should be reduced To reduce the noise we need to know how much noise is being radiated and by what machine Therefore the sound power of the individual machines must be known and then ranked by their sound power Once located the noise sources of the machine making the most noise can be measured to locate the individual components radiating noise Sound power can be derived from sound pressure only under carefully controlled conditions where special assumptions are made about the sound field Specially constructed rooms such as anechoic or reverberant chambers fulfil these requirements but the noise source must be placed in these rooms to calculate sound power which may have been logistically impossible or cost prohibitive All this can be done in situ with intensity measurements In situ measurement with Type 2270 G can provide the necessary information to determine a course of action for complying with appropriate local a
8. 118 Sound Intensity Software BZ 7233 User Manual 117 Appendix B B 1 B 2 Measurement and Calculated Parameters Measurement Parameters The following spectrum parameters are measured within Elapsed Time e Mean Pressure Z weighted e Sound Intensity Z weighted The following single value parameters are measured within Elapsed Time e Start Time e Stop Time e Overload Percent e Time Remaining The measurement parameters are saved on a segment together with the pressure residual intensity index Up to 15 x 15 segments can be saved within a surface Up to 25 surfaces can be saved with a project Calculated Parameters The following spectrum parameters are calculated per segment e Mean Pressure A weighted e Sound Intensity A weighted e Pressure Intensity Index e Dynamic Capability e Sound Power Z weighted e Sound Power A weighted e Scan Difference ISO 9614 2 and ECMA 160 e Repeatability Limit ISO 9614 2 and ECMA 160 only 118 Sound Intensity Software BZ 7233 User Manual The following single value parameters are calculated per segment from the frequency bands excluding frequency bands with Excluded band set e Mean Pressure Z weighted e Mean Pressure A weighted e Sound Intensity Z weighted e Sound Intensity A weighted e Pressure Intensity Index Z weighted e Pressure Intensity Index A weighted e Sound Power Z weighted e Sound Power A weighted The following
9. Selected Surface Individual surface parameters Surface Name Surface Height Rows Columns Segment Height and Segment Width are valid for the selected surface Surface Name Enter a name for the selected surface Surface Height Enter the total height for the area to be measured This will auto populate if Rows and then Segment Height were stipulated Surface Width Enter the total width for the area to be measured This will auto populate if Columns and then Segment Width were stipulated Rows Enter the number of rows into which the total height will be segmented Columns Enter the number of columns into which the total height will be segmented Segment Height Enter the height of the individual segments This will auto populate if Rows and then Surface Height were stipulated Segment Width Enter the width of the individual segments This will auto populate if Columns and then Surface Width were stipulated Repeat specifying individual surface parameters for each surface NOTE You can set Height and Width in metres SJ or feet US UK set in Preferences gt Regional Settings gt Dimension Unit 10 Set Signal Recording requires license for Signal Recording Option BZ 7226 NOTE You can record the signal in a 2 channel WAV file for further analysis using Briiel amp Kjer s PULSE Multi analyzer platform or just for listening and validation purposes Recording Mode Off or Automat
10. Sound Intensity Software BZ 7233 User Manual The following table outlines the requirements of the standard in the first column and provides the means to fulfil these requirements using the Type 2270 Hand held Sound Intensity System Required by Standard 2270 Solution Calibration e The instrument including the probe shall comply with IEC 1043 Make Pressure and Phase Calibration Make a pressure calibration of the microphones using calibrators Type 4197 3541 3541 A or 4231 Make a phase calibration using calibrators Type 4197 or 3541 e Make a phase verification and measurement of the pressure residual intensity index using calibrators Type 4197 or 3541 If non compliant Yellow smiley IEC61043 Compliance failed Field Check e Measure the intensity level at the same point two times one of the times with the probe reversed The difference at the band with the maximum level shall be less than 1 5 dB and the values shall have opposite directions Use Field Check e Perform the built in Field Check procedure If non compliant Yellow smiley for Field Check failed Detailed view of difference and limit available Stationary Noise Source Check e No method given Use Temporal Variability Check e Perform the built in Temporal Variability check procedure If non compliant Yellow smiley for Temporal variability too high e Detailed view of normalized standard devi
11. The frequency will be marked by the spectrum display cursor 2 Tapping on the X axis 3 Selecting Exclude band from the drop down menu 4 The band will be excluded and marked by an x Tapping on the X axis when at an excluded band will display the Include band option NOTE Calculations of Totals are made for the non excluded frequency bands For specific standard s requirements see section 6 16 Displaying Measurement Parameters Measurement parameters are displayed in spectrum surface temporal variability and compass views These measurement displays are optimised to support the measurement process Spectrum In the spectrum the A and Z weighted total values are calculated based on the frequency bands in the spectrum excluding the bands marked with an x Excluded 42 Sound Intensity Software BZ 7233 User Manual Fig 4 1 The Spectrum view Intens AF Wh 500 H 36 1 de 130 7 gt 90 SUO Hy IA 63 250 _ eae Intensity AF 10 a Surface 16 26 26 The displayed data in the Spectrum display is defined by the measurement state see Table 4 4 and user defined parameters The information and selected parameters are 1 Measurement state W stopped gt playing or paused and duration These are not selectable here and are displays of the actual state of the measurement 2 Surface selection This selection determines the displayed surface 3 Reference spectrum selection This
12. the Spacer line reads 12 mm c Tap and select Transducers If the transducers are not in the system see section 3 2 step 5 Set Input for instructions on entering a new microphone pair 3 Tap and select Calibration The Calibration screen will appear Fig 3 9 16 Sound Intensity Software BZ 7233 User Manual Fig 3 9 Calibration screen dB I 1 I 120 140 _ 160 4 On the Details tab a Tap Calibrator select 4297 b Tap Calibration level and enter 94 dB 5 On the Level tab a Tap Ambient Temperature and enter the current temperature NOTE You can set temperature to Celsius SJ or Fahrenheit US UK set in Preferences gt Regional Settings gt Temperature Unit b Tap Ambient Pressure and enter the current barometric pressure 6 Press the Start button on the Type 4297 control panel see Fig 3 10 The sine wave 251 2 Hz LED indicator should light If it does not the batteries need to be replaced as described in Chapter 1 of the Sound Intensity Calibrator Type 4297 User Manual CHAPTER 3 Setting up the Analyzer 17 Fig 3 10 Type 4297 control panel showing the start sine wave broadband noise selector buttons and LED indicators NOTE If a sound intensity probe is not placed in the chamber the unit will shut down after approximately 10 seconds 7 Allow at least 5 seconds for the pressure to equalise and for stabilisation of the feedback circuit 8 Tap Calibrate and wa
13. 1439 UA 1440 including Dual Preamplifier Extension Handle with 4189 Microphone 10 pin Stem Integral Cable ZE 0032 Microphone Preamplifier 100129 1 6 Sound Intensity Software BZ 7233 User Manual 3 1 3 1 1 Fig 3 1 CHAPTER 3 Setting up the Analyzer 7 Chapter 3 Setting up the Analyzer Connecting the Microphones to the Analyzer Mounting the Microphones NOTE Before mounting the microphones please observe the following precautions e Do not touch the microphone diaphragm with anything it is very delicate e Gently screw on the microphones to avoid damaging the threads e Keep dust and foreign matter off the microphone diaphragm The microphones normally used with this software are the phase matched 1 2 Sound Intensity Microphone Pair Type 4197 which require an external polarization voltage of 200 V To mount a microphone pair 1 Identify Microphone Type 4197 Part1 and Part2 tube connected to cable A and cable B and the compression joints Fig 3 1 1 Microphone part numbers 2 Cables A and B 3 Compression joints 100137 100138 2 Loosen the bottom compression joint screw and gently retract the bottom tube connected to the cable marked B 3 Gently screw Microphone Type 4197 Part2 onto the bottom tube 4 Select the desired spacer for more information in spacer selection see section 6 9 7 and gently screw the side of the spacer with the metal insert onto Microphone Type 418
14. 55 5 1 Displaying Result Parameters cccccecceseceeeeeeeeeeeenneeeeeeeeeeeeeaaeeeeeeeeeeeenaeeees 55 5 2 Examine Results 0 0 cccceceeescecccceeeeeeeeseeeeeeeeeeeesseeeeaeeeeeeesensaeeeaeeeseeseseeeeeeeeeeeegs 60 5 3 Validation cccc wAi aie cite aieeao eaei aie p adeved ii ie iaai 64 5 4 Creating New Projects Based on Recalled Projects cscceeseeeeeeeeeees 64 5 5 Exporting Post processing and Reporting cceeeeeseeeeeeeeeeeeeeeeeeneeeeeeeeess 65 CHAPTER 6 Theory and Practice aj ceaseticseccctehstanaleticnccalasadaendSiseds eadesnandaclactededieacalaweedemlasaeial 67 6 1 Sound Pressure and Sound POwWe ccccccceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeesesneeeetees 67 6 2 What is Sound Intensity ccccccccceceeeeeeeeeceeeeeeeeeeeecaeeeeeeneeeseeeneeeeseeeeeesees 67 6 3 Why Measure Sound Intensity ccccccceeeeeceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeseeeeeeeees 68 6 4 SOUN FieldSis isn eie e e ie e aa iei eia ee 68 6 5 Particle Velocity oe ccc cc cccccccccceceecceeeeeeeeeeceeeeeeeeeeeeeeeeeeeeeeeeececeeeeseeeeeeeeseeeeeeeeeteegs 70 6 6 How is Sound Intensity Measured ccccccceeeeeceeeeeeeeeeeeeeeeeeeeeeeeeeneeeteeeees 70 6 7 The Measuring System c cccceeececeeeeeceeeeeeeeeeeeeeeeeeeeceeeeeseceeeeeeeneeeeeesneeeeeees 71 6 8 Reference Levels ienis ie ni Pe ee i i aE 73 6 9 Pressure intensity IndeX cece ccecceeeeeeeeeceeeeeeeeeeeeaaeeee
15. BZ 5503 is included with Type 2270 for easy synchro nisation of setups and data between PC and Type 2270 BZ 5503 is supplied on DVD BZ 5298 ON LINE DISPLAY OF TYPE 2270 DATA Measurements on Type 2270 can be controlled from the PC and displayed on line with the PC using the same user interface on the PC as on Type 2270 DATA MANAGEMENT Explorer Facilities for easy management of instruments users jobs projects and project templates copy cut paste delete rename create Synchronisation Project templates and Projects for a specific user can be synchronised between PC and Type 2270 USERS Users of Type 2270 can be created or deleted EXPORT FACILITIES Excel XML Projects or user specified parts can be exported to Microsoft Excel Type 7752 Projects can be exported to PULSE Noise Source Identification Type 7752 version 16 1 or higher for mapping and sound power calculation Images superimposed on surfaces are automatically exported and shown in 7752 The pre defined box will be displayed in 7752 in 3D TYPE 2270 SOFTWARE UPGRADES AND LICENSES Controls Type 2270 software upgrades and licensing of Type 2270 applications INTERFACE TO TYPE 2270 USB LAN or Internet connection USB Connection Hardware versions 1 3 USB ver 1 1 e Hardware version 4 USB ver 2 0 LICENSE MOVER To move a license from one analyzer to another use BZ 5503 together with License Mover VP 0647 LANGUAGE User Interface in Chi
16. Dynamic capability p l index is checked against dynamic capability for each frequency band in each segment surface and total surface If non compliant Yellow smiley for Dynamic Capability too low for each frequency band Three grades of accuracy Detailed views of p I index and Dynamic Capability available for each segment surface and total surface Field Uniformity Evaluate Criterion 2 N gt C F 4 for each frequency band e Three grades of accuracy e Definition N number of segments C defined in table Field uniformity N gt C F4 checked If non compliant Yellow smiley for Sound Field is non uniform for each frequency band Three grades of accuracy Detailed views of Field uniform and Field uniform Limit available for the total surface Extraneous Noise Evaluate F3 Fo F3 Fos 3 for each frequency band e Definition FF log Extraneous noise Extraneous noise checked against 3 dB for each frequency band in the total surface If non compliant Yellow smiley for Extraneous Noise too high for each frequency band Detailed view of Extraneous Noise available for the total surface 90 Sound Intensity Software BZ 7233 User Manual Calculation of Sound Power e Calculate the sound power from each segment by multiplying the sound intensity by the area of the segment e Calculate the total sound power by adding the sound power from all
17. Theory and Practice 87 6 16 Using Sound Power Standards 6 16 1 ISO 9614 1 1993 E Determination of Sound Power Levels of Noise Sources using sound intensity Part 1 Measurement at Discrete Points ISO 9614 1 is an appropriate standard for on site determination of sound power It is based on measurements where the sound intensity is measured over a surface using discrete points Frequency Range 63 Hz to 4 kHz in 1 l octaves and 50 Hz to 6 3 kHz in 1 3 octaves Initial Test 1 Calibrate the intensity system as described in section 3 3 2 Check the instrumentation for proper operation by performing a field check as described in section 3 3 4 3 Check whether or not the sound field is stationary by measuring the temporal variability as described in section 4 6 The Measurement Method 1 Define a measurement surface of at least 10 segments around the test source 2 Perform a measurement at each segment 3 Evaluate a The dynamic capability compared to the p I index of the measurement b The level of extraneous noise c the non uniformity of the sound field 4 Calculate the total sound power by summing the results of all segments The pressure intensity p I index and sound power are calculated in Type 2270 per segment per surface and for the total surface as 2 gt Po P 10log ___ ressure Olog N 2 U l Intensity 10log o gt i Po SA p I index F 10log n E Olog n Sound Powe
18. Total single value parameters are calculated based on all the surfaces excluding Excluded segments e Total Sound Power Z weighted e Total Sound Power A weighted e Total Intensity Z weighted e Total Intensity A weighted e Total Mean Pressure Z weighted e Total Mean Pressure A weighted e Total Pressure Intensity Index Z weighted e Total Pressure Intensity Index A weighted e Field Uniform A weighted Field non uniformity indicator ISO 9614 1 only 120 Sound Intensity Software BZ 7233 User Manual index INDEX 121 A Active sound fields Aural Feedback Auto range eeeceeeeeeceneeeeeeeeeeteaeeeteseeeeteneeeees 11 111 B Back erase Pushbutton sseeeeeeeeeeeseeeerreernenn 40 Background noise ccccceeseeeeeeeeeeeeeeeeeeneeeseneeeess 85 Broadband Values c cecceeeeeeeeeeeeeeeeeteeeeeneeeess 49 Cc Calibrate Calibration aae eTe nea ALES EEA ANAE LEAT TRIEME IAA Sound PreSSUle inniu hyaan 13 17 Compass Nah ersten il ee ee ca ee 48 Controlling Measurements cccccceceeeeeeeeeneeeeseeeeeeeeaeeeeeas 39 Conventions Used in this Manual cceeeeees 1 D Diffuse field iskari nea 69 Directivity characteristics ccccecsceeeeteeeeeeeeeees 72 Dynamic range cccccceeeeeeeeeeeeeeeeeeeeeeeeeeneeeeeeaeeess 80 E Exclude Include Bands Exclude include Segments Extended high frequency
19. because this quantity is independent of the environment and is the unique descriptor of the noise emission of a sound source What is Sound Intensity Any piece of machinery that vibrates radiates acoustical energy Sound power is the rate at which energy is radiated energy per unit time Watts Sound intensity describes the rate of energy flow through a unit area The unit for sound intensity is Watts per square metre Sound intensity is a vector quantity having both magnitude and direction and sound pressure is a scalar quantity having magnitude only Usually intensity is measured in a direction normal at 90 to a specified area through which the sound energy is flowing Specifically sound intensity is the time averaged rate of energy flow per unit area In some cases energy may be travelling in opposite directions If there is no net energy flow during the averaging time there will be no net intensity However in this case there will be a reactive intensity as described in section 6 4 3 a 6 3 6 4 6 4 1 Sound Intensity Software BZ 7233 User Manual In Fig 6 1 the sound source is radiating energy All this energy must pass through an area enclosing the source Since intensity is the power per area it is easy to measure the normal spatial averaged intensity over an area that encloses the source and then multiply it by the area to find the sound power Why Measure Sound Intensity On the factory floor sound press
20. cccceesseeeeeeteeeeeseeees Extension Stem 1s ieeeesi saan dela Extension Stem UA 1439 eseese F Field Cn6ek iieii chien anon 21 Finite difference approximation 71 Free field earar a ataa ea aerias 68 74 Frequency Limit LOW i hin o ua ERR 79 Frequency range s esesseessssssessssrresererrerinnsrrnsernns 75 G Grid n aitare adaki a a 46 47 H Handle trond Avda kedeedo aai a s 9 Handle with Integral Cable UA 1440 eee 8 High frequency limit How to Change Parameter Values cseeee 41 How to Use this Manual 0 00 eee ceteris 1 BeQiINNGIS nisniaraidin a n ahuan 2 Experienced USers s sniyiisisesiiididrniyiiiiiaiaidiiia 2 l JEC 61043 etaar ana anes eee 79 Introduction rasene ir a E E 1 M Measurement limitations 00 0 0 eerste 75 Measuring system ccccccceeeeeeeeeeeeeeeeeneeeseeneeeees 71 Microphone Pair cccescceeeeteeeeeeeeeeeeeeeteeeeeees 11 Type A197 pirani eaa eaten 7 Microphone Type cccccceceeeeeeeeeeeeeeneeeeeneeeeteneeeees 11 Mounting Microphones onto Probe n 7 Probe onto AnalyZer cccccceeeseeeeeseeeeeeeeeeeteaees 8 Mounting the Microphones on the Probe 7 N Navigation Pushbuttons and Stylus USC Of inii cares ena anne ed ceveess 41 Near field sii asia doer ani readin aiaa eai 70 O On screen Feedback nrs isarsssisrenisiirrrrriscareiraniinante 41 P Parameters wrists in r a A
21. different image e Tap Brighter or Darker to adjust the brightness of the image until the required readability has been obtained e Hide Image removes the image from the background until the menu is reopened and Show Image is selected e Selecting Close closes the menu CHAPTER 4 Measuring 49 NOTE The selected image is common to the Surface views in Measurement and Result displays however brightness and whether the image is switched on or off are set individually for each Surface display NOTE For making images using a camera and inserting them as annotations on the project in BZ 5503 and transferring the project to Type 2270 the image format must be JPG and contain exactly 640 x 480 pixels with resolution of 96 dpi bit depth 24 4 2 4 Spectrum Parameters The data to be displayed in the Surface and Spectrum displays relates directly to the measurement process i e Intensity and Pressure spectra and the p I index spectrum Table 4 3 3 Instantaneous Time Averaged Available parameters Intensity AF Intensity A Pressure AF Pressure A Intensity ZF Intensity Z Pressure ZF Pressure Z p l index F p l index Dynamic Cap Scan Difference Repeatability Limit Instantaneous spectra are displayed when the measurement is in Stopped state no un saved measured data and averaged spectra are displayed while measuring and when in Paused state Table 4 4 Displayed data by view
22. found to have better frequency response and directivity characteristics than side by side back to back or face to face without solid spacer arrangements The choice of spacer depends on the frequency range to be covered Probe Directivity Characteristics The ideal directivity characteristic for the sound intensity probe looks two dimensionally like a figure of eight pattern known as a cosine characteristic see Fig 6 4 Top View Side View 90 270 980326 1 Since pressure is a scalar quantity an ideal pressure transducer should have an equal response no matter what the direction of sound incidence that is we need an omnidirectional charac teristic In contrast sound intensity is a vector quantity With a two microphone probe we do not measure the vector we measure the component in one direction along the probe axis The full vector is made up of three mutually perpendicular components at 90 to each other one for each coordinate direction For sound incident at 90 to the axis there is no component along the probe s axis as there will be no difference in the pressure signals Hence there will be zero particle velocity and zero intensity For sound incident at an arbitrary angle O to the axis the intensity component along the axis will be reduced by the factor cos O This reduction produces the cosine directivity characteristic Fig 6 5 Fig 6 5 The effective spacer distance is red
23. is available in the On line Help installed on Type 2270 Experienced Users of Acoustic Measurement Equipment The manual is designed so that you do not have to read all of it to be able to use the instrument It is built around the most frequently used operations which are as follows e A brief introduction to sound intensity and Type 2270 G Chapter 2 e Preparing the Analyzer for measurements Mounting microphones setting analyzer parameters calibration and tutorials Chapter 3 e Making measurements Measurement control display measured parameters feedback validation and creating new projects from recalled projects Chapter 4 e Results Display result parameters map data validate recall projects exporting post processing and reporting Chapter 5 e A thorough background in the theory and practice of sound intensity Chapter 6 e Specifications Chapter 7 e Setup Parameters Appendix A e Measurement and Calculated Parameters Appendix B It is recommended that you read the entire manual for appropriate procedures on how to use Type 2270 and obtain accurate results Chapter 2 2 1 2 1 1 Concept and Contents of Type 2270 G Sound Intensity In simple terms sound pressure is what a person hears in a given area Sound pressure is the result of sound power being influenced by environment at the moment of measurement Sound power is the rate of the energy emitted from the sound source and sound intensity is a time
24. is limited by clipping in the microphones and the electrical circuitry If this occurs Overload will be indicated For the Microphone Pair Type 4197 this typically happens at 153 5 dB for a sinusoidal signal at 1 kHz At low levels the dynamic range is limited by the self generated noise from the microphones the preamplifiers and the analyzer Here sound pressure and sound intensity measurements behave differently CHAPTER 6 Theory and Practice 81 Sound pressure measurements have a well defined behaviour at low levels Measurement levels lower than the self generated noise level are not possible When the signal approaches the self generated noise level the influence from the noise adds as a bias error of to the measured level For sound intensity measurements there is not a well defined lowest level There is no bias error from the self generated noise What happens when the level is reduced is that the spread of the measurements coming from the self generated noise is increased The amount of spread that is introduced for a given level of self generated noise depends on the intensity level the pressure level the spacer length the frequency the filter bandwidth and the averaging time For a given amount of spread in theory the level of intensity and pressure can be lowered 3 dB each time the averaging time is doubled In practice this holds for averaging times up to 15 minutes or longer based on circumstances This r
25. is not stated Briiel amp Kj r recommends checking whether or not the sound field is stationary by measuring the temporal variability as described in section 4 6 The Measurement Method 1 Define two measurement surfaces around the source under test one divided into N 2 segments the other divided into N segments N gt 8 2 Perform a measurement at each segment of the two surfaces 3 Evaluate the convergence index difference in total sound power based on N 2 and N segments 4 if the convergence index is higher than allowed double the number of segments and repeat steps 2 and 3 until the convergence index check succeeds 5 Evaluate a The dynamic capability compared to the p I index of the measurement b The parasitic noise indicator in Type 2270 referred to as extraneous noise 6 Calculate the total sound power by summing the results of all segments based on the N surface The pressure intensity p I index and sound power are calculated in Type 2270 per segment per surface and for the total surface as 2 gt Si P Po S gt SUi p S Pressure 10log Intensity 10log 96 Sound Intensity Software BZ 7233 User Manual f S Si Pi Po p I index Fpl 10log 5 10log YS S Sound Power 10log X S 0 10 where p pressure of segment i p 20 uPa N number of segments J Intensity of segment i l 1pW m and S area of segment i The standard recom
26. of sound power It is based on measurements where the sound intensity is measured over a surface using the scanning method Frequency Range 63 Hz to 4 kHz in 1 l octaves and 50 Hz to 6 3 kHz in 1 3 octaves Initial Test 1 Calibrate the intensity system as described in section 3 3 2 Check the instrumentation for proper operation by performing a field check as described in section 3 3 4 3 The sound field shall be stationary however the standard does not specify how to check this Briiel amp Kj r recommends checking the temporal variability described in section 4 6 The Measurement Method 1 Define a measurement surface of at least four segments around the test source 2 Perform a measurement at each segment 3 Evaluate a The partial power repeatability of the two scans b The dynamic capability compared to the p I index of the measurement c The level of extraneous noise 4 Calculate the total sound power by summing the results of all segments The pressure intensity p I index and sound power are calculated in Type 2270 per segment per surface and for the total surface as 2 gt Si P Po Pressure 10log es gt SiUi 0 Intensity 10log age 2 gt Si Pi Po gt SiGi 40 p I index FpI 10log 10log S S Sound Power 10log X S 0 10 where p pressure of segment i p 20 uPa N number of segments J Intensity of segment i l 1pW m and S area of segment i a
27. of the segment 9 Press 4 and hold the probe in the centre of the segment for the full time period that was stipulated in Setup 10 Data are auto saved and the segment selector is positioned on the next segment 11 Follow the segment measurement path stipulated in Setup for the remainder of the measurement See Fig 3 36 Fig 3 36 Left Three measurements have been made you are ready to measure at segment R1 C4 Right You are measuring at R1 C4 the segment has turned green When paused it turns yellow and when saved it turns blue and the position moves to next segment Bottom R1 C5 ready for measurement 12 Tap Result gt CHAPTER 3 Setting up the Analyzer 39 13 Examine the saved data in the segments select to display A weighted total from Power A which gives a good overview of the data If a smiley appears at a frequency it will also appear in the A weighted total In Fig 3 37 Left there is only a single smiley at R1 C3 Tap at the smiley in the line above the surface to display the problem In this case the dynamic capability is too low see Fig 3 37 Right 14 Display using Contour and Curve maps and show maxima Fig 3 37 Left Quality indicator Smiley in segment R1 C3 Right Smiley description IQ c C2 G C cs a Surf Power A 72 5 E 15 Tap Spectrum to display the spectrum at R1 C3 Note that the dynamic capability is too low for 80 Hz
28. only in this segment Because it does not have any effect on the Power for the surface there is no smiley for the Surf PwrA readout Fig 3 38 Fig 3 38 Spectrum view with smiley on Power A A 72 5 dB A 57 0 dB 4 mM Surf Poa A EE Power A 57 0 d8 Start Time 13 09 2010 13 23 40 40 Sound Intensity Software BZ 7233 User Manual Chapter 4 4 1 4 1 1 Measuring Measurement Control The stylus and navigation pushbuttons are used for setting up the analyzer navigating through the screens and managing the results A number of items that appear on the screen parameter values or icons can be selected updated and activated For instance a new parameter value can be selected from a drop down list The selection and activation of items on the screen can be done in two ways 1 Tapping once on the item on the screen will select and activate it 2 Moving the field selector around using the navigation keys until the item you want is highlighted then pressing the Accept pushbutton vy to activate it You can choose to use the stylus or the pushbuttons depending on your preference and the measurement situation Use of Pushbuttons for Controlling Measurements The design of the analyzer is such that the layout of the pushbuttons has been optimised for single handed operation Reset Pushbutton Use the Reset pushbutton to reset a measurement If the measurement is paused i e Pau
29. outside Tot A freq range set on A total Increase Accuracy In order to guarantee upper limits for uncertainties of the sound power levels determined certain actions have to be taken if criteria 1 2 and 3 are not fulfilled See Hints for Improving Accuracy 6 16 3 ECMA 160 1992 Determination of Sound Power Levels of Computer and Business Equipment using Sound Intensity Measurements Scanning Method in Controlled Rooms ECMA 160 is very similar to ISO 9614 2 The differences are e Frequency Range 125 Hz to 4 kHz in 1 1 octaves and 100 Hz to 6 3 kHz in 1 3 octaves e For A weighted data no conditions for the frequency bands below the bottom end of the frequency range e Grade of Accuracy Engineering only CHAPTER 6 Theory and Practice 95 6 16 4 ANSI S12 12 1992 Engineering Method for the Determination of Sound Power Levels of Noise Sources using Sound Intensity ANSI S12 12 is an American standard for on site determination of sound power It is based on measurements where sound intensity is measured over a surface at fixed points or by scanning over each segment Frequency Range 125 Hz to 8 kHz in 1 1 octaves and 100 Hz to 10 kHz in 1 3 octaves Initial Test 1 Calibrate the intensity system as described in section 3 3 2 Check the instrumentation for proper operation by performing a field check as described in section 3 3 4 3 The sound field shall be stationary however a method for testing
30. post processing software suite including Measurement Partner Suite BZ 5503 for data transfer setup and remote display included with your analyzer and PULSE Noise Source Identification software Type 7752 PULSE version 16 1 or later for mapping and sound power calculation 1 ABAN 3p W m a m 5 Ha so For Help press FL b dm 66 Sound Intensity Software BZ 7233 User Manual Chapter 6 6 1 6 2 Theory and Practice Sound Pressure and Sound Power A sound source radiates power and causes sound pressure So what we hear is sound pressure caused by the sound power emitted from the source A sound pressure that is too high may cause hearing damage So when trying to quantify human response to sound such as noise annoyance or the risk of hearing loss pressure is the obvious quantity to measure It is also relatively easy to measure The pressure variations detected by the eardrum that we perceive as sound are the same pressure variations that are detected by the diaphragm of a condenser microphone The sound pressure that we hear or measure with a microphone is dependent on the source the distance from the source and the acoustic environment in which sound waves are present This in turn depends on the size of the room and the sound absorption of the surfaces So only measuring sound pressure cannot necessarily quantify how much noise a machine emits The machine s sound power is the important factor
31. result is satisfactory press amp b Tf the result was unsatisfactory press gt and remeasure the segment 9 Select the next surface for example Left Repeat steps 6 through 9 for the remainder of the measurement 10 Tap Result gt 11 Tap Result gt and select the Spectrum tab and set the Spectrum Parameters to Power A and Tot Pwr A If the A total reading in Tot Pwr A does not have a smiley there are no warnings for the calculated A total However if it has a smiley you must investigate the segment spectra or surface spectra in more detail Spectrum Result tab with parameters set to Power A and Tot Pwr A 500 Hz als SOO Hz 4k 10k AZ 43 4 dB 55 6 dB 9 6 dB Spectrum 14 06 24 12 Examine the saved data in the segments looking for smileys in different frequencies or with A or Z weighting 13 Tap Spectrum and use the display cursor to examine different frequencies for different segments and exclude or include bands to pinpoint problems The Tot Pwr A parameter is the sum of the sound power from the individual segments 28 Sound Intensity Software BZ 7233 User Manual If a yellow smiley is present below a frequency band tap in the spectrum to select this band with the cursor then tap the smiley at the cursor readout to determine the cause If the dynamic capability is too low examine the p I index of the individual segments Select Dynamic C and p I index and step
32. selection determines the data displayed by the reference frequency bar graph item 6 4 Main spectrum selection This selection determines the data displayed by the main frequency bar graph item 7 and data displayed in the Surface view 5 Y axis The Y axis represents the level at a given frequency Tapping the Y axis creates a drop down menu with the options presented in Fig 4 2 Fig 4 2 Y axis options Fig 4 3 Spectrum Table CHAPTER 4 Measuring 43 AM 11 4 dB amp 14 4 B AZ Auto Zoom Auto zooms to an optimised level of detail and visibility Zoom In Increases the detail of the Y axis Zoom Out Reduces the detail of the Y axis Auto Scale Places the viewing window of the display to show the max level Scale Up Shifts the viewing window higher on the Y axis Scale Down Shifts the viewing window lower on the Y axis Spectrum Table Opens the Spectrum Table see Fig 4 3 Close Closes the menu Spectrum Table 315Hz2 2 5dB 6 Reference bar graph A bar graph of the data stipulated in item 3 according to the selected segment item 19 and frequency indicated by the spectrum frequency cursor item 15 44 Sound Intensity Software BZ 7233 User Manual 7 Main bar graph A bar graph of the data stipulated in item 4 according to the selected segment item 19 and frequency indicated by the spectrum frequency cursor item 15 For Pressure spectra the bars in the graph are normally
33. state Blue Saved data Yellow Unsaved measurement paused Green Measuring Smileys Quality indicator offering hints and guidance Averaged value the presence and detail of the data are dependant on grid resolution see Grid Tap on the segment to Select the segment Exclude Include the segment in the measurement process and calculations for the Surface parameters Copy the data in the segment to the clipboard CHAPTER 4 Measuring 47 Cut the data in the segment to the clipboard Paste the data from the clipboard to the segment Delete the segment 7 Smiley Quality indicator offering hints and guidance 8 Averaged value Displays the time averaged value at the displayed frequency band and segment item 4 The presence and detail of the data are dependant on grid resolution see Grid 9 Camera icon Tap E to incorporate images see section 4 2 3 10 X axis Grid columns 11 Grid See Grid 12 Level dBs defined by measurement parameter see item 3 segment see item 15 and spectrum cursor display see item 4 13 Quality indicator Smiley Offers hints and guidance in the parameters defined by measurement parameter see item 3 segment see item 15 and spectrum cursor display see item 4 This smiley can be tapped for a display of more detailed information More smiley information is presented in Table 4 6 14 Result gt Click here for the Results displays 15 Segment Segment select
34. the Generator settings Intensity CF The source for the output socket can be set to the Intensity ZF Intensity XF X A C or Z frequency weighting Generator F Fast time weighting The intensity level is output as a DC voltage between 4 47 and 4 47 V Intensity levels with positive direction will output positive voltages Intensity levels with negative direction will output negative voltages Set Lowest Level 0 V to the level and lower levels which will output 0 V Output Gain is 20 dB V The possible output range is then 4 47 x 20 dB 89 4 dB however the max output depends on the range setting Low or High Range the sensitivity of the intensity probe the Ambient Pressure and the Ambient Temperature Hint In Calibration Details View you can read Max Input Level Ch 1 this is a good approximation of the possible max output NOTE If output signal is not needed set Source Off to economise power use 116 Sound Intensity Software BZ 7233 User Manual Lowest Level 0 V 20 to 160 dB The intensity level can be output as a DC voltage between 4 47 and 4 47 V Set Lowest Level 0 V to the level and lower levels which will output 0 V Output Gain is 20 dB V A 8 Headphone Signal APPENDIX A Setup Parameters 117 Parameter Values Comment Aural Feedback Off Determines whether the aural feedback is
35. the reference levels there is a small difference in levels The actual difference depends on the value of the characteristic impedance pc of the medium in which it is measured Here pis the density and c the speed of sound in the medium The characteristic impedance pc depends on temperature and ambient pressure If pc 400 Nsm then Lp Ly Ly but at reference environmental conditions 20 C and 1013 25 hPa pc 414 Nsm therefore Lr L 0 15 dB at reference environmental conditions Pressure intensity Index In practice we will not measure in the direction of propagation in a free field so there will be a difference between the pressure and intensity levels This difference is an important quantity known as the pressure intensity index p I index pl L L High p I index levels correspond to low intensity levels compared to the pressure levels This happens when measurements are done in a diffuse field or a reactive field near field and when measurements are done perpendicular to the direction of propagation in a free field So a high p I index level indicates a low level of energy flow in the measured direction Pressure residual Intensity Index The finite difference approximation requires that the two microphones in the probe and the two channels in the analyzer have the same phase response If the same signal is fed to the two microphones the analyzer should ideally measure zero intensity However the phase
36. the two microphones are placed face to face causes resonance in the small cavity between the spacer and the membrane of the microphone This in turn causes an increase in pressure for sound incidence along the probe axis The pressure increase does to some extent compensate for distortion of the directional characteristic of the probe caused by the finite difference error Therefore the operational frequency range for a Briiel amp Kj r Probe can be extended to an octave above the limit determined by the finite difference error if the length of the spacer between the microphones equals the diameter of the microphones and if the levels are compensated with an optimized frequency response for the microphone pair This CHAPTER 6 Theory and Practice 7 phenomena was originally discovered by the authors of A Sound Intensity Probe for Measuring from 50 Hz to 10 kHz F Jacobsen V Cutanda and P M Juhl Briel amp Kj r Technical Review No 1 1996 In Fig 6 7 Fig 6 9 it can be seen how Type 2270 G Sound Intensity System extends the frequency range to include the 10 kHz 1 3 octave frequency band when using a 12 mm spacer and Microphone Pair Type 4197 Fig 6 7 Theoretical sound intensity directional characteristics according to the finite difference theory with a 12mm spacer at 50 Hz and 3 15 4 5 6 3 8 and 10 kHz 980323 e 78 Sound Intensity Software BZ 7233 User Manual Fig 6 8 Typical uncom
37. through the segments using lt or gt in order to locate segments that need to be remeasured NOTE In Fig 3 21 the Surf Pwr A has no smiley which means that the smileys on the individual segments do not affect the total surface Fig 3 21 Result spectrum with smileys l 4k 10k AZ 14 Select the Total tab and view the results for each surface in the box view The Total Power is stated below the box in the Power A parameter 3 4 4 Sound Power Measurement Standard ISO 9614 2 With 2270 G turned on Sound Intensity template selected and a microphone pair set up and selected see section 3 2 1 Perform calibration see section 3 3 2 Tap the far right section of the Template line Fig 3 3 then tap S Pwr Ensure that Standard is set to ISO 9614 2 3 Set Grade of Accuracy e g Engineering tap gt Setup gt Standard gt Grade of Accuracy NOTE Precision grade is only specified in ISO 9614 1 4 Set Measurement Control tap gt Setup gt Measurement Control section 3 2 Fig 3 22 Measurement Control setup Input Standard Bandwidth SI Task Sound Power Mapping Measurement Mode Automatic Preset Time 00 00 20 Segment Order Automatic Save Surface Signal Recording Output Socket Signal Headphone Signal CHAPTER 3 Setting up the Analyzer 5 Set Surface tap gt Setup gt Surface see sections 3 2 and 4 2 2 Fig 3 23 Surface setup
38. total surface as 2 gt Si Pi Po S gt SUi y S Pressure 10log Intensity 10log 100 6 16 6 Sound Intensity Software BZ 7233 User Manual ESP gt S 0 o I index FpI 101 101 p I index p Olog 5 Olog 5 Sound Power 10log X S 0 10 where p pressure of segment i p 20 uPa N number of segments J Intensity of segment i l 1pW m and S area of segment i e Extraneous noise is calculated and checked against a maximum of 3 dB for each frequency band in the total surface e A detailed view of extraneous noise is available for the total surface gt Dn Hints for Improving Accuracy Extraneous Noise ee If one or more of the following status codes appear take the associated action s Dynamic Capability Failed and Extraneous Noise too High Suitable for ISO 9614 2 ECMA 160 ANSI 12 12 and None Halve the average distance of the measurement surface from source to not less than a minimum average value of 10 cm and double the scan line density or Shield the measurement surface from strong extraneous noise sources by means of a screen or Reduce the adverse influence of the reverberant sound field by introducing additional absorption into the test space at locations remote from the source Dynamic Capability Failed and Extraneous Noise too High Suitable for ISO 9614 1 In the presence of significant extraneous noise and or strong reverberation reduc
39. type and measurement state State View Spectrum Surface Stopped Instantaneous spectra Instantaneous value Measuring Average spectra Average value Paused Average spectra Average value The measurement parameters will automatically switch from instantaneous e g Intens AF to averaged e g Intensity A when measurement state changes from stopped to measuring The measurement parameters will automatically switch back from averaged to instantaneous when measurement state changes from paused to stop 50 Sound Intensity Software BZ 7233 User Manual 4 2 5 Single Values Single values measurement parameters are displayed below the spectrum Tap on them to chose parameters for your reference See Table 4 5 for the full list of options You can select between General parameters such as Start Time etc and Totals of the spectra calculated from the frequency bands excluding the Excluded bands Table 4 able 5 Instantaneous Averaged General Available single value measurement parameters Intensity AF Intensity A Start time Pressure AF Pressure A Stop time p I index AF p l index A Overload Intensity ZF Intensity Z Time remaining Pressure ZF Pressure Z p l index ZF p l index Z 4 3 NOTE The Total values are the same values as the A and Z bands in the spectrum Document your Measurement You can document your measurement by adding metadata or annotations lik
40. very light on a dark background dependant on chosen color scheme For Intensity spectra the bands with positive direction are also light on a dark background however bands with negative direction are shown as colored bars 8 Band information This area provides visual cues to the state of the individual bands Xs indicate excluded bands and smileys are quality indicators 9 Single values parameter Below the graph two single measurement parameters are displayed Tap them to choose parameters for your reference See section 4 2 5 for details 10 Single value parameter Refer to section 4 2 5 for details 11 Single value parameter corresponding result Refer to section 4 2 5 for details 12 Single value parameter corresponding result Refer to section 4 2 5 for details 13 X axis Represents the frequency bands 14 Spectrum totals The totals A and Z of the spectra are calculated from the frequency bands excluding the Excluded bands 15 Spectrum frequency cursor Selects the frequency displayed in item 15 16 Frequency Stipulated by the spectrum frequency cursor item 15 17 dB level dB level based on the measurement parameter items 3 and 4 the selected segment item 19 and frequency indicated by the spectrum frequency cursor item 15 Readouts for values with a direction have a or behind the dB to indicate the direction of the measured value 18 Result gt Click here for the Results displays 19 Segmen
41. 10 spectra and calculate the normalized standard deviation e Verify F4 lt 0 6 Use Temporal Variability Check e Perform the built in Temporal Variability check procedure e If non compliant Yellow smiley for Temporal Variability too high e Detailed view of normalized standard deviation of 10 measurements together with limit Surface Definition Define a measurement surface of at least 10 segments around the source under test Define Surfaces and Segments e Divide the total measurement surface into a number of surface grids consisting of a number of segments Define the dimensions of the surfaces Probe Positioning Position the probe At the centre of the segment e With the probe pointing towards the source e With acoustic centre of probe at the surface Use image e Capture an image of the device under test and overlay it on the surface grid e Use image and grid as guideline for positioning the probe CHAPTER 6 Theory and Practice se Averaging Time The averaging time must be at least 400 B seconds where B is the filter bandwidth View Yellow smileys for Averaging Time too short appears if averaging time is less than 400 B seconds Dynamic Capability Evaluate Fo criterion 1 e Fo lt Ly for each frequency band pressure intensity index for the total surface should be less than the dynamic capability e Three grades of accuracy
42. 26 Electrical equipment for measurement control and laboratory use EMC requirements CISPR 22 Radio disturbance characteristics of information technology equipment Class B Limits IEC 61672 1 IEC 61260 IEC 60651 and IEC 60804 Instrumentation standards NOTE The above is only guaranteed using accessories listed in this Product Data EMC Immunity EN IEC 61000 6 2 Generic standard Immunity for industrial environments EN IEC 61326 Electrical equipment for measurement control and laboratory use EMC requirements IEC 61672 1 IEC 61260 IEC 60651 and IEC 60804 Instrumentation standards NOTE The above is only guaranteed using accessories listed in this Product Data Temperature IEC 60068 2 1 amp IEC 60068 2 2 Environmental Testing Cold and Dry Heat Operating Temperature 10 to 50 C 14 to 122 F Storage Temperature 25 to 70 C 13 to 158 F Humidity IEC 60068 2 78 Damp Heat 93 RH non condensing at 40 C 104 F Recovery time 2 4 hours Mechanical Non operating IEC 60068 2 6 Vibration 0 3 mm 20 m s2 10 500 Hz IEC 60068 2 27 Bump 1000 bumps at 400 m s2 IEC 60068 2 27 Shock 1000 m s2 6 directions Enclosure IEC 60529 1989 Protection provided by enclosures IP20 112 Sound Intensity Software BZ 7233 User Manual Appendix A Setup Parameters A 1 Input Range Setting Auto Range Spacer and Transducer Parameter Values Comment Input Top Socket Rear Socket
43. 7 Part1 5 Gently screw Microphone Type 4187 Part1 onto the top tube connected to cable A 8 3 1 2 3 1 3 3 1 4 Sound Intensity Software BZ 7233 User Manual 6 Slightly loosen the compression joint for the top tube so that the tube can twist 7 Gently push the bottom tube towards Microphone Type 4187 Part twisting the top tube as necessary to align the microphone pair until the nib on the end of Type 4187 Part2 slots into the hole on the spacer The general position of the tubes should as shown in Fig 3 2 8 Tighten both compression joints Conecting the Probe to the Analyzer NOTE Do not mount the probe directly onto the Analyzer If you do so by mistake you will need to remove it by gently prising the probe out with a small screwdriver The probe should be mounted onto the Extension Stem UA 1439 which is attached to the Handle with Integral Cable UA 1440 which is then connected to the Analyzer Mounting the Probe onto the Handle The probe can be connected directly to the handle if necessary i e space considerations but because it is difficult to remove this is not recommended To mount the probe onto the handle simply insert the probe plug into the input socket of the handle making sure it snaps into position Mounting the Probe onto the Extension Stem To mount the probe onto the extension stem insert the LEMO connector at the bottom of the probe into the socket of the extension stem pres
44. 7233 are required to run the system REFERENCE CONDITIONS Reference Sound Pressure Level 94 dB Reference Frequency 250 Hz Reference Temperature 20 C Reference Static Pressure 1013 25 hPa Reference Relative Humidity 65 INSTRUMENTATION STANDARDS Conforms with the following standards IEC 61043 1993 12 Class 1 IEC TS 62370 2004 05 IEC 61260 1995 07 plus Amendment 1 2001 09 1 1 octave Bands and 1 3 octave Bands Class 0 e ANSI S1 11 1986 1 1 octave Bands and 1 3 octave Bands Order 3 Type 0 C e ANSI 81 11 2004 1 1 octave Bands and 1 3 octave Bands Class 0 SOUND POWER STANDARDS Conforms with the following standards e ISO 9614 1 1993 E e ISO 9614 2 1996 E ANSI S12 12 1992 ECMA 160 1992 FREQUENCY RANGE 1 1 and 1 3 octave spectral measurements based on a linear electrical frequency response Z freq weighting 1 1 octave Band Centre Frequencies 31 5 Hz 8 kHz 1 3 octave Band Centre Frequencies 25 Hz 10 kHz FREQUENCY WEIGHTING Z and A weighted total results are based on weighted summation of spectral bands in the frequency range 22 Hz 11 3 kHz Frequency bands can be manually excluded from calculation PRESSURE RESIDUAL INTENSITY INDEX The minimum pressure residual intensity index for the analyzer the Processor in IEC 61043 measured with pink noise at a band filtered level of 114 dB in the high range is shown in Fig 7 1 103 104 Sound Intensi
45. ACE AND PROJECT DEFINITION e Setups and measurements for a given measurement session and measurement of temporal variability are stored in a project e A project can contain up to 25 surfaces Custom or 5 surfaces pre structured as a box Box CHAPTER 7 Specifications 105 A surface is defined as a plane with a number of segments of equal size organised as a rectangle Each segment can contain one measurement Height and width dimensions can be set for the segments or set for the total surface For ANSI 12 12 each surface is doubled using N 2 and N segments Dimensions can be set in SI units or US UK units A surface can contain up to 15 x 15 segments Definitions of surface and segments can be modified at any time before during or after a measurement Measurements can be stored in previously measured segments overwriting existing data a warning is displayed Individual segments can be deleted The measured data of a segment can be copied to other positions IMAGES e Image annotations can be selected as background for surfaces The selected part of the image can be adjusted to match the surface The image is displayed in black and white and can be made darker or lighter for optimal visibility together with grid and readouts on the screen CALCULATIONS e Sound power can be calculated for each segment surface or total surface Frequency bands or segments can be manually included in or excluded from calculations The follo
46. Averaging Time too short appears Convergence Index Evaluate Lwy 2 Lwy Compute the difference between the sound power calculated from the first set of measurements and the second set twice as many Compare the difference to the limits specified in the standard at each frequency band of interest If the convergence index is too high go to next step Double the number of segments make a measurement on each segment and calculate the sound power Repeat this step until the convergence index is within the limits for each frequency band of interest Convergence Index Total Power based on N and N 2 segments is compared to the limit If non compliant Yellow smiley for Convergence index failed for each frequency band Detailed views of Convergence index and Convergence index limit available for the total surface If Convergence index fails then double the number of rows or columns measure these segments and evaluate again a Sound Intensity Software BZ 7233 User Manual Dynamic Capability e Evaluate phase indicator D53 equal to p l index e Check that D52 pressure residual intensity index D53 gt 7 for each frequency band Dynamic Capability e p l index is checked against dynamic capability for each frequency band in each segment surface and total surface If non compliant Yellow smiley for Dynamic Capability too low for each frequency band e Set Grade of Accurac
47. R Particle velocity 4 Post processing and Reporting sceeeeeees 65 Preamplifier ID NO cccsceeeeeeeeeeeeeeeeeeneeeeeneeees 11 Pressure gradient c cccescceeeeeeeeeeeeeeeeneeeteeneeeees Pressure residual intensity index ceeeeeee Pressure Residual Intensity Verification Remove from Handle cccccccccccessesseeeeeeeeesneea Pushbuttons BaCk 6r Ses vicissoscsen oesessbecthscs aE cote 40 ROSCU itu seucnei arene nein Aaa ants 39 DAVO la rete Mik Aiceee Ais dive seta iia eens 40 Slart Pause 2 ieee ena ain ate 40 Q Quality Indicator priania au 51 R Range setting 2 8 accented aces 111 Reactive Sound fields ccccccccssssceceeeeessssteeeeees 69 Reference l vels 2 4 cacti acan anatase 73 Reset Pushbutton sciiicet onai 39 S Save PUSMDULON sivi e arani SCANNING inas Adai ia SS Segment Order cccccccececeeeeeceeeeeeeeeeeeneeeeseneeeesaees Selecting a microphone pair cceceeeeeeeeeeeees Serial NO ciiesccssesencvstentasens Setups ative eis ei eee aa ee eee Bandwidth v casceccsccesccoccinesterecencascencenecetenecnesvtenscees Generator Headphone Signal Microphone soositi tiesia a anane Standard Surface Sound intensity Sound Intensity Calibrator eseeeeeeeeeeeer eeen SOUN POWERS faa aisle ee ei ties Sound pressure cece ceeeeeeeeeeeeeeeeeeeeceeeseeeeee
48. Technical Documentation sound Intensity Software BZ 7233 For use with Hand held Analyzer Type 2270 User Manual Briel amp Kj r lt gt Sound Intensity Software BZ 7233 For use with Hand held Analyzer Type 2270 User Manual BE 1841 14 December 2013 Safety Considerations This apparatus has been designed and tested in accordance with IEC EN 61010 1 and ANSI UL 61010 1 Safety Requirements for Electrical Equipment for Measurement Control and Laboratory Use This manual contains information and warnings which must be followed to ensure safe operation and to retain the apparatus in safe condition Special note should be made of the following Safety Symbols A The apparatus will be marked with this symbol when it is important that you refer to the associated warning statements given in the manual Protective Earth Terminal A Hazardous Voltage Explosion Hazard The equipment is not designed to be used in potentially explosive environments It should not be operated in the presence of flammable liquids or gases Warnings e Switch off all power to equipment before connecting or disconnecting their digital interface Failure to do so could damage the equipment e Whenever it is likely that the correct function or operating safety of the apparatus has been impaired it must be made inoperative and be secured against unintended operation e Any adjustment maintenance and repair of the open apparatus under voltag
49. The Reference Spectrum J and Main Spectrum E icons indicate which spectrum belongs to which parameter Spectrum Parameters Available parameters e Intensity The intensity for the segment or surface is shown e Pressure The mean pressure for the segment or surface is shown e Power The sound power is calculated from intensity and the area of the segment surface e p I Index Pressure intensity index and Dynamic capability With this display you can verify the p I index of the measurement together with the Dynamic capability Table 5 1 Single Values Single values measurement parameters are displayed below the spectrum Tap on them to choose parameters for your reference See Table 5 2 for the full list of options You can select between General parameters such as Start Time etc and Totals of the spectra calculated from the frequency bands excluding the Excluded bands NOTE The Total values are the same values as the A and Z bands in the spectrum CHAPTER 5 Viewing Results 63 ae spectrum Segment Surface Total result parameters Power A Surf Pwr A Tot Pwr A Intensity A Surf Int A Tot Int A Pressure A Surf Pres A Tot Pres A Power Z Surf Pwr Z Tot Pwr Z Intensity Z Surf Int Z Tot Int Z Pressure Z Surf Pres Z Tot Pres Z p index Surf p I idx Tot p l idx Dynamic C Surf Dyn C Tot Dyn C Scan di
50. ZI 0055 on top of the coupler 16 Switch on the sound source 17 Tap on the Phase tab at the bottom of the screen and the Phase calibration screen will appear Fig 3 11 18 Tap Calibrate and wait for it to finish NOTE Tapping Calibrate includes the verification process but verification can be performed individually To do so tap Verify and let the verification continue for 2 minutes and press Stop Verify 19 Tap Yes to accept the new calibration and verification There should be no yellow smileys 20 Switch off the sound source Using Type 4231 For full details on the use of this calibrator please refer to Sound Calibrator Type 4231 User Manual BA 5341 Sound Pressure Level Calibration 1 Select the correct adaptor for the microphone diameter you want to calibrate and fit it to the calibrator see Table 1 1 of Sound Calibrator Type 4231 User Manual 2 Switch on the Analyzer and select the Sound Intensity Project Template 3 Ensure that the Analyzer is properly set up for calibration with the calibrator to be used a Tap and select Setup b Expand Input by tapping it and ensure that the Input line reads Top Socket and that the Spacer line reads 12 mm CHAPTER 3 Setting up the Analyzer 21 c Tap H and select Transducers If the transducers are not in the system see section 3 2 step 5 Set Input for instructions on entering a new microphone pair 4 Tap and select Calibration from
51. ability Check Perform the built in temporal variability check procedure Detailed view of normalized standard deviation of 10 measurements together with limit CHAPTER 6 Theory and Practice 97 Surface Definition Define a measurement surface around the source under test and divide the surface into N 2 and N segments Define Surfaces and Segments Divide the total measurement surface into a number of surfaces consisting of a number of segments Define the dimensions of the surfaces and segments Type 2270 automatically creates surfaces with double the number of segments Point Measurement Position the probe At the centre of the segment e With probe pointing towards the source e With the acoustic centre of probe at the surface Scanning Perform the scan e Ata steady pace e With the probe pointing towards the source e With the acoustic centre of the probe at the surface e Follow the scan path accurately The averaging time must be at least 30 s for frequencies at or below 160 Hz and at least 10 s for frequencies at or above 200 Hz Use image Use aural feedback View Capture an image of the device under test and overlay it on the surface grid Use image and grid as guideline for positioning the probe Count number of beeps while moving the probe to and fro Keep your eyes on the probe while listening to the progress of the scan If non compliant Yellow smiley for
52. accessory typically 5 hours NOTE It is not recommended to charge the battery at temperatures below 0 C 32 F or over 50 C 122 F Doing this will reduce battery lifetime CLOCK Back up battery powered clock Drift lt 0 45s per 24 hour period WARM UP TIME From Power Off lt 2 minutes From Standby lt 10s for prepolarized microphones WEIGHT AND DIMENSIONS 650 g 23 oz including rechargeable battery 300 x 93 x 50 mm 11 8 x 3 7 x 1 9 including preamplifier and microphone USERS Multi user concept with login Users can have their own settings with jobs and projects totally independent of other users PREFERENCES Date time and Number formats can be specified per user LANGUAGE User interface in Catalan Chinese People s Republic of China Chinese Taiwan Croatian Czech Danish English Flemish French German Hungarian Italian Japanese Korean Polish Portuguese Romanian CHAPTER 7 Specifications 109 Russian Serbian Slovenian Spanish Swedish and Turkish HELP Concise context sensitive help in English French German Italian Japanese Korean Polish Portuguese Romanian Serbian Slovenian and Spanish UPDATE OF SOFTWARE Update to any version using BZ 5503 through USB or update via Internet Hardware versions 1 3 the latest version only e Hardware version 4 any version from 4 0 and up WEB PAGE Connect to the instrument using an Internet Browser supporting Java scri
53. an 3 dB e Only mandatory for Engineering grade e Definition IPI Fy i0log amp 5 LF Extraneous noise Extraneous noise checked against 3 dB for each frequency band in the total surface If non compliant Yellow smiley for Extraneous Noise too high for each frequency band Detailed view of Extraneous Noise available for the total surface Calculation of Sound Power e Calculate the sound power from each segment by multiplying the sound intensity by the area of the segment e Calculate the total sound power by adding the sound power from all the segments Calculation of Sound Power Sound power is automatically calculated for the displayed segment surface or total surface Calculation of A total e Calculate A total from all the frequency bands but do not use bands not fulfilling criteria 1 and or 2 e Uncertainty in any frequency band more than 10 dB below A total is irrelevant e Frequency bands with a sum more than 10 dB below A total may be ignored e A weighted bands below 50 Hz or above 6 3 kHz should be more than 6 dB below the total value A total is calculated on all segments surfaces and total surface using frequency bands not marked with Dynamic Capability too low or Extraneous Noise too high Only the smileys relevant for the calculation of A total are marked on the A total A weighted band levels below 50 Hz and above 6 3 kHz checked If too high A smiley High levels
54. an be changed to Left Right and Forward by tapping on the probe display 56 Sound Intensity Software BZ 7233 User Manual Chapter 5 Viewing Results 5 1 Displaying Result Parameters The Result displays consist of Total Surface and Spectrum displays optimised for viewing results To open the Results displays tap Results gt on the Spectrum or Surface tabs in the measurement displays To exit Results and return to the measurement displays tap EJ 5 1 1 Spectrum Fig 5 1 Results Spectrum display 1 Surface selection This selection determines the displayed surface 2 Reference spectrum selection This selection determines the data displayed by the reference frequency bar graph item 15 3 Main spectrum selection This selection determines the data displayed by the main frequency bar graph item 14 and data displayed in the Surface view 56 Sound Intensity Software BZ 7233 User Manual 4 Y axis The Y axis represents the frequency band level Tapping the Y axis creates a drop down menu with the options presented in Fig 5 7 5 Spectrum frequency cursor Selects the frequency displayed in item 14 and item 15 6 X axis Represents the frequency bands 7 Single values parameter Below the graph three single measurement parameters are displayed Tap on them to choose parameters for your reference Refer to section 5 3 for details 8 Single value parameter Refer to section 4 2 5 for details
55. and turn it counterclockwise and remove the protection plug This exposes the intensity probe holder and the black plastic button that gives access to the battery compartment 14 Sound Intensity Software BZ 7233 User Manual Fig 3 6 The unit is open and ready to receive the sound intensity probe 2 Place the Sound Intensity Probe into the holder Fig 3 7 Fig 3 7 Sound Intensity Probe in holder CHAPTER 3 Setting up the Analyzer 15 NOTE For best results the spacer should be removed But the spacer should be used to set the correct distance by placing it between the microphone pair without screwing in the spacer see Fig 3 8 tightening the compression joint to hold the slider in place and then removing the spacer for placement into the calibrator Fig 3 8 3 Spacer as a guide Z n e 010048 3 Close the unit by reversing the procedure described above Sound Pressure Level Calibration Type 2270 G is now ready for sound pressure calibration NOTE Minimise vibrations at your work surface equipment during calibration as vibrations will falsely affect readings 1 With the sound intensity probe connected to Type 2270 G switch on the Analyzer and select Sound Intensity Project Template 2 Ensure that the Analyzer is properly set up for calibration with the calibrator to be used a Tap and select Setup b Expand Input by tapping it and ensure that the Input line reads Top Socket and that
56. ather complex relationship between many factors makes it difficult to give a picture of where the lowest level is without assuming some of the factors As an example use the following as levels of accuracy for the measurement e For the sound pressure 0 5 dB bias error e For the sound intensity 95 confidence interval of 0 7 dB which corresponds to a 95 confidence interval of 1 dB for the repeatability of two measurements e Assume that the signal itself is fully deterministic and without any spread Then assume the following e Transducer set to 4197 without windscreen e Analyzer set to Low Range 1 3 octave and an averaging time of 30 sec e The pressure intensity index of the signal is between 0 and 10 dB Under all these assumptions the lower limit of the dynamic range for the sound intensity measurements can be determined and plotted in Fig 6 12 82 Sound Intensity Software BZ 7233 User Manual Fig 6 12 The lower limit of the dynamic range for sound intensity measurements under all the assumptions defined above 80 70 60 12 mm Spacer a oO Level dB S 50 mm spacer 30 Ea 20 10 100 1x10 1x10 Frequency Hz 110654 The curves in Fig 6 12 consist of two parts The decreasing part at low frequencies and the slightly increasing part at high frequencies The first part is the soun
57. ation of 10 measurements together with limit Surface Definition e Define a measurement surface of at least 4 segments around the source under test Define Surfaces and Segments e Divide the total measurement surface into a number of surfaces consisting of a number of segments Define the dimensions of the surfaces CHAPTER 6 Theory and Practice Scanning Perform the scan e Ata steady pace e With the probe pointing towards the source e With acoustic centre of probe at the surface e Follow the scan path accurately The scan must have a duration of at least 20 seconds Make two orthogonal scans of each segment Use aural feedback e Count number of beeps while moving the probe to and fro e Keep your eyes on the probe while listening to the progress of the measurement Listen e Aural feedback pitch rises one octave after 20 seconds e If non compliant Yellow smiley for Averaging Time too short Press the Pause Continue button and view the status panel to keep track of the scans Repeatability Partial power repeatability criterion 3 Perform two scans on each segment then check every frequency band for the following e The difference between the power levels of the two scans must be within a certain limit e Two grades of accuracy For all segments If in any one frequency band the sum of the partial powers failing to meet Criterion 3 is more than 10 dB b
58. ave the measurement data together with the calibration data onto the selected segment on the surface of the project The current project template including all the screen settings and setup information is updated in the project Pressing Q will affect the pause and running states In both cases the measurement state will be stopped shortly after pressing the pushbutton W displayed Back erase Pushbutton Use the Back erase pushbutton to reset the paused measurement If used when the current measurement is running then the measurement will be stopped and reset If used with ISO 9614 2 and ECMA 160 the latest scan will be reset 4 1 2 4 2 4 2 1 CHAPTER 4 Measuring 41 Use of Stylus for Controlling Measurements Segment Order Segments will become sequentially active in the measuring process according to the pattern designated in Setup gt Measurement Control gt Segment Order however specific segments can be selected manually by tapping the segment with the stylus Exclude include Segments Before measurement begins individual segments can be excluded by tapping the segment with the stylus and selecting Exclude from the drop down menu The segment can be re included by tapping the segment again and selecting Include Exclude Include Bands Exclude include frequency bands from calculation of the Total values by 1 Selecting the frequency band to exclude by tapping it above the X axis with the stylus
59. can be studied on site Sound Fields Sound in a region is classified according to the manner and the environment in which the sound waves travel Some examples will now be described and the relationship between pressure and intensity discussed This relationship is precisely known only in the first two special cases described below free and diffuse field The Free Field This term describes sound propagation in idealised free space where there are no reflections These conditions hold in the open air sufficiently far enough away from the ground or in an anechoic room where all the sound striking the walls is absorbed see Fig 6 1 Free field propagation is characterized by a 6dB drop in sound pressure level and intensity level in the direction of sound propagation each time the distance from the source is doubled This is simply a statement of the inverse square law The relationship between sound pressure and sound intensity magnitude only is also known It gives one way of finding sound power which is described in the International Standard ISO 3745 Fig 6 1 Free and diffuse fields 6 4 2 6 4 3 CHAPTER 6 Theory and Practice 69 vA Free Field p i oa Diffuse Field a 2 P rms k 4pc 980275 1 The Diffuse Field In a diffuse field sound is reflected so many times that it travels in all directions with equal magnitude and probability This field is appr
60. cators for each frequency band in each spectrum These include letters and smileys see Table 4 6 Table 4 6 dst Code when Quality indicators Quality Exported to and Smileys Indicator Smiley Description ej Code Excel using BZ 5503t x X Excluded band 1 O pE Overload 512 D amp Dynamic capability too low 2 C E Copied data 1024 U 5 Underrange 32 F 5 Field check failedt 64 a IEC 61043 compliance failed 16384 R Repeatability failed 4 E 5 Extraneous noise too high 8 S E Averaging time too short 16 V 5 Convergence index failed 256 H E High levels outside Tot A freq range 2048 T 5 Temporal variability too high 8192 N amp Sound field is non uniform 32768 The Quality Indicators first column are shown in the spectrum table single parameter view only see Fig 5 8 T Negative Direction has code 4096 The codes are added together for values with more than one code Only in Field Check view a Only in Phase Calibration view Smileys are shown on e All displays of results e The Project as the smiley for the calculated A Total for the total Surface For explanations of smileys tap on the smiley in question or for the small smileys below the frequency bands in the spectrum select the frequency band with the cursor and tap on the smiley in the cursor readout a 4 6 4 7 Sound Intensity Software BZ 7233 User Manual Hint To get an over
61. d selected see section 3 2 1 Perform calibration see section 3 3 2 Tap the far right section of the Template line Fig 3 3 then tap S Pwr Ensure that Standard is set to ANSI 12 12 3 Set Grade of Accuracy as requested e g Engineering tap gt Setup gt Standard gt Grade of Accuracy 4 Set Measurement Control tap gt Setup gt Measurement Control see section 3 2 Fig 3 27 Measurement Control setup Standard Measurement Contro SI Task Sound Power Mapping i Measurement Mode Automatic Preset Time 00 00 20 Segment Order Automatic Save off Signal Recording Output Socket Signal Headphone Signal 15 33 22 CHAPTER 3 Setting up the Analyzer 33 5 Set Surface tap gt Setup gt Surface see sections 3 2 and 4 2 2 Fig 3 28 Surface setup 16 00 10 According to ANSI 12 12 two measurement surfaces must be defined around the source under test one divided into N 2 segments the other divided into N segments N 2 8 To set up a simple surface two rows and two columns a b c Fig 3 29 Left Pop up dialog Right Adjust setting options Select Total Surface Type Custom Set Surface Height I m and set Surface Width 1 m Set Rows N 2 2 and Columns N 2 2 Tapping the parameter to the right of each brings up the pop up dialog shown in Fig 3 29 To set the number place the check in the checkbox for Adjust setting and tap OK
62. d intensity part It is limitted by the spread in the sound intensity measurement The second part is the sound pressure part It is limited by the bias error in the sound pressure measurement Only the sound intensity part can be lowered if the averaging time is increased 6 12 6 How to Assess the Lower Limit of the Dynamic Range The example in section 6 12 5 shows how complex it is to assess the lower limit of the dynamic range To help ease this process Sound Intensity System Type 2270 G introduces an underrange indication while measuring The underrange indication is shown as a smiley for each frequency band Type 2270 knows its settings and the selected transducer and calculates the limits from that information CHAPTER 6 Theory and Practice 83 The underrange indication uses same criteria for the levels of accuracy of the measurement as in section 6 12 5 e For the sound pressure Maximum 0 5 dB bias error e For the sound intensity 95 confidence interval of maximum 0 7 dB e Assume that the signal itself is fully deterministic and without any spread It is important to understand the limitations of the underrange indication as follows e The limits are based on typical self generated noise and transducer sensitivities e If there is no underrange indication You can conclude that your sound pressure measurement has a bias error less than typical 0 5 dB maximum 1 dB You cannot conclude that your sound intensity mea
63. dard specific information is available Fig 4 4 The Measurement Status Field contains alternate displays while the standard is set to ISO 9614 2 or ECMA 160 ISITY ISO 9614 2 S Pwr 52 9 dB 00 H2 41 2 dB 4k 10k AZ 638d 51 1 dd 25 Measurement status Displays Play green background or Pause yellow background 26 Duration of current scan 27 Row and column Segment currently being measured 28 Action Tracker During measurement Scanning is displayed at completion of first scan of segment Start Scan 2 is displayed at completion of Scan 2 Store Segm is displayed 46 Sound Intensity Software BZ 7233 User Manual 4 2 2 Surface The Surface display presents measurements in a grid format of rows and columns representing the plane area measured see Fig 4 5 Fig 4 5 The Surface view 1 Measurement state W stopped gt playing or paused and duration These are not selectable here and are displays of the actual state of the measurement 2 The surface name 3 Main spectrum measurement parameter selection This selection determines the data displayed by the main frequency bar graph section 4 2 1 item 7 and displayed in the selected segment 4 Spectrum frequency cursor Selects the frequency of the parameter displayed the segment and also in item 15 of section 4 2 1 5 Y axis Row see item 15 6 Segments Segments display information dependant on their
64. dard wil Disk Proj wo and c SI Task 2 Measurements can be stored on the internal disk or as an optional storage method insert an SD card in the SD Card slot a USB memory stick in the USB Standard A slot hardware version 4 only or CF card in the CF card slot hardware versions 1 3 only The slots are located on the connector panel described in Hand held Analyzers Types 2250 and 2270 User Manual You will be notified that a memory card has been inserted select Yes to change the default measurement path to the memory card 3 Tap the Main Menu icon BH and select Explorer Create a job folder for the measurements and set the default measurement job path as described in Chapter 6 of Hand held Analyzers Types 2250 and 2270 User Manual 4 Tap and select Setup The Setup screen Full tab will appear see Fig 3 4 Fig 3 4 The SETUP screen See Appendix A for details on the setup parameters Output Socket Signal Headphone Signal Generator CHAPTER 3 Setting up the Analyzer 11 5 Set Input Input Top Socket Range Setting Low Range or High Range NOTE Pressing before a measurement institutes Auto Range which automatically selects High or Low range as appropriate Spacer Between 6 and 200 mm 12 mm is recommended Input Ch 1 Enter the microphone pair being used and specify Windscreen Correction if applicable NOTE Selecting a microphone pair for Input Ch 1 will apply the same set
65. dex for sound intensity measurements errors from the phase perspective can be examined and translated into the pressure intensity index perspective Both the microphones and the electrical components in the measurement channels change the phase of the signals Any difference in the change in the two channels will yield phase mismatch errors The amount of phase mismatch between the two channels in the analyzing system determines the low frequency limit At high frequencies the change in phase across the spacer distance is big For example the phase change is 65 at 5 kHz over a 12 mm spacer On the other hand at low frequencies the change in phase across the spacer distance is small At 50 Hz the change of phase over a 12 mm spacer is only 0 65 For accuracy to within 1 dB the phase change over the spacer distance should be more than five times the phase mismatch The international standard for sound intensity instruments IEC 61043 sets minimum requirements for the instruments pressure residual intensity index These requirements can be translated into phase errors for the whole system giving 0 086 at 50 Hz and 1 7 at 5 kHz 80 Sound Intensity Software BZ 7233 User Manual 6 12 4 Improving the Pressure residual Intensity Index Using a longer spacer between the microphones extends the frequency range to a lower low frequency limit but this reduces the high frequency limit If phase mismatch errors are in stead reduced by c
66. display 3 Tap on OX ensure that the image conforms to the measurement surface 4 Press 3 to capture the image 5 Press y to save the image or 02 to reject the image and capture the image again 6 Tap the image and tap Select for Surface to place the image as the surface background 7 Tap and drag the stylus across the image to crop image that will be measured to the defined surface CHAPTER 3 Setting up the Analyzer 37 3 4 7 Mapping Measurement With Type 2270 G turned on Sound Intensity template selected and transducers set up and selected see section 3 2 1 Perform calibration see section 3 3 2 Set SI Task to S Pwr then set the standard to None 3 Set Measurement Control tap gt Setup gt Measurement Control see section 3 2 Fig 3 34 Measurement Control E Input setup Standard Bandwidth SI Task Sound Power Mapping if Measurement Mode Automatic Preset Time 00 00 20 Segment Order g Automatic Save off Surface Signal Recording Output Socket Signal Headphone Signal 4 Set Surface tap gt Setup gt Surface see sections 3 2 and 4 2 2 Fig 3 35 Surface setup 16 00 10 5 Tap El to exit Setup 6 Apply an image if desired see section 3 4 6 38 Sound Intensity Software BZ 7233 User Manual 7 Tap Surface tab 8 Beginning with the segment indicated on the Surface display position the probe to measure from the centre
67. e frequency band are displayed together with quality indicators Curve Displays curves of equal levels from a selectable frequency band Contour Displays colors between the curves of equal levels from a selectable frequency band For Curve and Contour Hide show maxima Zoom in or out auto scale transparency adjustment and two color scales TOTAL For display of surface results organised in a list ora exploded box e Include exclude a surface from calculation of total surface results TOTAL VALUES Single values per segment surface or total surface displayed as numbers Sound pressure sound intensity p I index sound power all Z or A weighted Single values for field non uniformity A weighted start time stop time overload time remaining CHAPTER 7 Specifications 107 General Specifications KEYBOARD Pushbuttons 11 keys with backlight optimised for measurement control and screen navigation ON OFF BUTTON Function Press for 1s to turn on When on press for 1s to enter standby or press for more than 5s to switch off STATUS INDICATORS Traffic Lights Red yellow and green LEDs show measurement status and instantaneous overload as follows e Yellow LED flash every 5s stopped ready to measure e Green LED flashing slowly awaiting trigger or calibration signal e Green LED on constantly measuring e Yellow LED flashing slowly paused measurement not stored e Red LED flashing quickly intermitt
68. e must be avoided as far as possible and if unavoidable must be carried out only by trained service personnel Do not dispose of electronic equipment or batteries as unsorted municipal waste e Itis your responsibility to contribute to a clean and healthy environment by using the appropriate local return and collection systems e Hazardous substances in electronic equipment or batteries may have detrimental effects on the environment and human health The symbol shown to the left indicates that separate collection systems must be used for any discarded equipment or batteries marked with that symbol e Waste electrical and electronic equipment or batteries may be returned to your local Briiel amp Kj r representative or to Briiel amp Kj r Headquarters for disposal Trademarks Microsoft and Windows Vista and Excel are registered trademarks of Microsoft Corporation Pentium is a trademark of the Intel Corporation Copyright 2013 Briel amp Kj r Sound amp Vibration Measurement A S All rights reserved No part of this publication may be reproduced or distributed in any form or by any means without prior written consent from Briiel amp Kj r Sound amp Vibration Measurement A S N rum Denmark Contents CHAPTER 1 IEFOGUCUION sc eee aaar ea aeria aeaea Aaa aaa aE a E 1 C1 Welcome isaha ous a ai e iaaa wees aa a i a aa i aeai 1 1 2 How to Use this Mantal 000 eee eeeecccceeeeeeeesseeeceeeeeeen
69. e spoken comments written notes or images to your project Please consult User Manual for Hand held Analyzers Types 2250 and 2270 BE 1713 chapter 3 5 for details In addition to project documentation you can define up to 30 metadata used on all the segments Tap the Paperclip icon i Fig 4 1 item 23 to access the Metadata text fields for the current segment You can define metadata for all segments here These are saved on the template The values of the metadata can then be set per segment If the icon is not visible there are no metadata or annotations Use the Analyzer s Up Arrow 4 Down Arrow Y pushbuttons to move the field selector to the Segment line and press the Right Arrow pushbutton to reveal the Paperclip icon Press the Accept pushbutton y to access the Annotations screen and enter metadata Fig 4 7 shows an example of segment metadata three have been defined The definitions and default values are common to all segments but you can select individual values per segment CHAPTER 4 Measuring 51 Fig 4 7 Example of segment metadata SEGMENT METADATA FREER At the top of the display Fig 4 7 are the surface selector and segment selection arrows for selecting other surfaces and segments You can also select segment metadata for display on the Measurement screen Fig 4 8 see also Fig 4 1 items 20 and 23 Fig 4 8 Measurement screen with Paperclip icons SOUND INTENSITY None
70. e system helps to assess dynamic range will also be discussed 6 12 1 The High Frequency Limit The upper frequency range is limited by the finite difference approximation used to measure the particle velocity section 6 6 1 The two microphones approximate the gradient of a curve to a straight line between two points If the curve changes too rapidly with distance the estimate will be inaccurate This will happen if the wavelength measured becomes small compared to the effective spacer distance Fig 6 6 a Fig 6 6 The approximation of the pressure gradient is inaccurate at high frequencies 6 12 2 Sound Intensity Software BZ 7233 User Manual Low Frequency Ap Ar dp or High Frequency Ap Ar dp or bicncecde ccee cooks 100135 Because it is the effective spacer distance Fig 6 5 that is compared to the wavelength the sound intensity directional characteristics for the probe will be distorted Most severely in the direction along the probe axis Fig 6 7 For a given effective spacer distance there will be a high frequency limit beyond which errors will increase significantly For accuracy to be within dB the wavelength measured must be greater than six times the spacer distance This corresponds to the following high frequency limits e 50mm spacer up to 1 25 kHz e 12 mm spacer up to 5 kHz e 6mm spacer up to 10 kHz Extended High Frequency Limit The fact that
71. e the average distance of the measured surface from the source to a minimum average value of 25 cm In the absence of significant extraneous noise and or strong reverberation increase the average measured distance to 1 m or Shield measurement surface from extraneous sources or take action to reduce sound reflections towards the source CHAPTER 6 Theory and Practice 101 Dynamic Capability Failed Suitable for ISO 9614 2 ECMA 160 and None Halve the average distance of the measurement surface from source to not less than a minimum average value of 10 cm and double the scan line density or Reduce the adverse influence of the reverberant sound field by introducing additional absorption into the test space at locations remote from the source Repeatability Failed Suitable for ISO 9614 2 and ECMA 160 Identify and suppress causes of temporal variation in field conditions or if this fails double the scan line density on the same segment Repeatability Failed and Extraneous Noise lt 1 dB Suitable for ISO 9614 2 and ECMA 160 Double the average distance from the measurement surface to the source keeping the same scan line density Convergence Index Failed Suitable for ANSI 12 12 Double the number of segments on the surface Temporal Variability too High Suitable for All Standards Take action to reduce the temporal variability of extraneous intensity or measure during periods of less variability or inc
72. eaees INDEX 122 Sound Pressure Calibration ccccccceeeee 14 17 Spatial averaging ccccccceeeseeeeeeeeeeeeeeeeeseeeeesseeees 84 Spectr staid he nee ADS Spectrum Table Start Pause Pushbutton eee ceesseeeeeeeeeeeteeee 40 Status Code PAE ENN EEE E EAE E E 51 Surfaces ae a esl ick ca lea 45 84 T TRANSGUCENS 2isci08s idl Ati tae needed LUtOnlalS 3 6 En A EE E ered PE eee hace aes TYPE IBAT ieena nae a iada aa es Type 4231 TY DO AQ a seach renee ec ees U Use of Stylus and Navigation Pushbuttons 0 41 V Verification Phasen tae a 19 VOY ee eea ea ea ad EE 17 19 Pressure Residual Intensity Index 006 16 WwW WECOME a a a Mog ce ee e A 1 HEADQUARTERS Briel amp Kj r Sound amp Vibration Measurement A S DK 2850 N rum Denmark Telephone 45 7741 2000 Fax 45 4580 1405 www bksv com info bksv com Local representatives and service organisations worldwide
73. eeeeeeeeeeeeesseeeeeeeeeenensseeeeeaees 1 CHAPTER 2 Concept and Contents Of Type 2270 G ccccccessseeeeeeeeeeeeseeeeeeeeneneeeeeeeeneeeeneeeees 3 2 1 SOUNGINtNSIY a 2 6 Aate eae kde bisa eed dent diet tee 3 2 2 Type 2270 G Overview cccccccceeeeeeeeeeeceeeeceeeeeeecaeeeeeceaeeesecaeeeeeceeeeeseneeeeeeaees 4 CHAPTER 3 Setting up the AmalyZet cccsseccccesseeeeeesseeeeeesseeeeeeesseeeeeesseneeeeseseeeeessenneeeeeees 7 3 1 Connecting the Microphones to the Analyzer c cceeeecceeeeeeeeeeeeeteeeteeeees 7 3 2 Setting up Type 2270 G eee eececceecccceeeeceeeeeeceeeeeceeeeeeeaeeeeeeaeeeeeeseeeeseneeeeesaaes 10 3 3 Calibrationuvs2 s c8 skate aie SUA on eR RTL SA 13 3 42 TutorialS 2 ich ehh cites Qe ach weenie aA ee Re 22 CHAPTER 4 MO ASUTID Gos setecestanicizcncnasenaivavtteansastuteiadeeaateraece pentariaiuencaedenanuasadeanaaeseteiavtanuaadsaweey 39 4 1 Measurement Control cccccccccssscccceceesssssseeeeeeeeeseseaeeeeeeeeseseesseeeeeeeesesenaaeees 39 4 2 Displaying Measurement Parameters ccccceeeeeeeenneeeeeeeeeeeeneeeeaeeeeeeeeeeeeaee 41 43 Aural Feedback ainina coe eh tee ee a aoa 49 BAe MAMI AUON coe AAE E E EE EOE E E E ea a Sate 51 4 5 Temporal Variability srai a a ee 52 a iR SR o p 1 0 C1 AE P E e hk nah a E E E tas Lane aah E 52 CHAPTER 5 Viewing FOSUNS ooo tvsnds sa ceed esd teten enced cccuecuenaaicateattcee neustth cnucnnwastnecearhdadenaudeniasaiees
74. eeeeeeesaaaeeeeeeeeeeeeaaeeeeeeeees 74 6 10 Pressure residual Intensity INGOX cccecceeeeeeeeeeenceeeeeeeeeeeenaeeeeeeeeeeeeeneaeeeeeeees 74 6 11 Dynamic Capability 2 00 2 ccceecccececceceeeeeceeeeeeeeeeeecaeeeeeeaeeeeecaaeeeseceeeeessneeeeeeaees 75 6 12 Measurement Limitations cccccccccccscessseececeeesseessseceeeeessaeaeeeeeeeessseaaeeees 75 6 13 Using Sound Intensity to Determine Sound Powet cccceeeeeeeeeeeeetees 84 6 14 Spatial AVeraging cccccceceeeccceeeeeeeeeeeeeeeeseeeeeeeeaeeeesceeeeeeeeeeeeeseeeeesseeeeeesaees 84 6 15 What about Background Noise ccccccececeeeeeeeeeeeeeeeeeeeeeeeeeceeeeeseneeeeeseaees 85 6 16 Using Sound Power Standards cc ccccccececeeeecceeeeeeeeeeeeeeeeeeesaeeeeseneeeeseaees 87 CHAPTER 7 SPECHIGBONS sosc ts ciiic te annainn enaa ana evel cian deie dead etn adaededneedeeasieele 103 APPENDIX A Setup Parameters 1 0 8 canst eee nek nae 111 A 1 Input Range Setting Auto Range Spacer ANC TrANSCUCED c E EE E A AS 111 OA Standards terete AE E A AA S A 112 1 ROR 1 1019 DALO I Ta EEE T A E ae he ae E 113 A 4 Measurement Control Measurement Mode Preset Time Segment Order Auto Save oo cccceccccccccseeeeeeceeceeeesueeeesseeeseesueueeseeeseueuuueeseeeeeeeeeeaaes 113 A 5 Surface DIMENSIONS ccc ccc ccccccccccccccceceeeeeeeeeeeeeeeeeeeeeeeeeececeeeeeeeeeeeeeeeeess 114 7 V0 mie e bee ee oe epee ee ee 115 A 7 Output Socket Signa
75. elow the sum of the partial powers satisfying Criterion 3 then the total sound power can still be calculated for that frequency band Repeatability e If non compliant Yellow smiley for Repeatability failed for each frequency band with scan difference above limit e Detailed views of Scan difference and Repeatability limit available e Three grades of accuracy available however select Engineering or Survey For all segments e This is automatically checked by the software If non compliant Yellow smiley for Repeatability failed is displayed for total sound power Dynamic capability Evaluate Fp criterion 1 Fp lt Lg for each frequency band pressure intensity index for the total surface should be less than the dynamic capability e Two grades of accuracy Dynamic capability e p l index is checked against dynamic capability for each frequency band in each segment surface and total surface If non compliant Yellow smiley for Dynamic Capability too low for each frequency band e Three grades of accuracy available however select Engineering or Survey e Detailed views of p I index and Dynamic Capability available for each segment surface and total surface s a Sound Intensity Software BZ 7233 User Manual Extraneous Noise Evaluate F criterion 2 e F4 3 dB for each frequency band negative partial power indicator for the total surface should be less th
76. ement data EXTERNAL DC POWER SUPPLY REQUIREMENTS Used to charge the battery pack in the instrument Voltage 8 24 V DC ripple voltage lt 20 mV Current Requirement min 1 5A Power Consumption lt 2 5 W without battery charging lt 10 W when charging Cable Connector LEMO Type FFA 00 positive at centre pin MAINS POWER SUPPLY Supply Voltage 100 120 200 240 VAC 47 63 Hz Connector 2 pin IEC320 BATTERY PACK Part No QB 0061 Rechargeable Li lon battery Voltage 3 7 V Capacity 5200 mAh nominal Typical Operating Time e Single channel gt 11 h screen backlight dimmed gt 8 5 h full screen backlight e Dual channel gt 7 5 h full screen backlight Use of external interfaces LAN USB WLAN will decrease battery operating time Battery Cycle Life gt 500 complete charge discharge cycles Battery Aging Approximately 20 loss in capacity per year Battery Indicator Remaining battery capacity and expected working time may be read out in and in time Battery Fuel Gauge The battery is equipped with a built in fuel gauge which continuously measures and stores the actual battery capacity in the battery unit Charge Time In analyzer typically 10 hours from empty at ambient temperatures below 30 C To protect the battery charging will be terminated completely at ambient temperatures above 40 C At 30 to 40 C charging time will be prolonged With External Charger ZG 0444 optional
77. ent overload calibration failed DISPLAY Type Transflective back lit colour touch screen 240 x 320 dot matrix Colour Schemes Five different optimised for different usage scenarios day night etc Backlight Adjustable level and on time USER INTERFACE Measurement Control Using pushbuttons on keyboard Setup and Display of Results Using stylus on touch screen or pushbuttons on keyboard Lock Keyboard and touch screen can be locked and unlocked VOICE ANNOTATIONS Voice annotations can be attached to measurements so that verbal comments can be stored together with the measurement Playback Playback of voice annotations can be listened to using an earphone headphones connected to the headphone socket Gain Adjustment 60 dB to 0 dB TEXT ANNOTATIONS Text annotations can be attached to measurements so that written comments can be stored with the measurement IMAGE ANNOTATIONS Image annotations can be attached to measurements Images can be viewed on the screen GPS ANNOTATIONS A text annotation with GPS information can be attached Latitude Longitude Altitude and position error Requires connection to a GPS receiver METADATA Up to 30 metadata annotations can be set per project text from keyboard or text from pick list number from keyboard or auto generated number Up to 30 metadata can also be set for the individual segments DATA MANAGEMENT Project Template Defines the display and measurement setup
78. ettings as the current project including the annotations e g image on Surface view and the segment metadata press the Reset pushbutton 7 while in Stopped state if all data in the current project have been saved and tap Yes on the pop up see Fig 5 10 Or reselect the Sound Intensity template Do you want to create a new project using the current template a ia ci Spectrum 20 03 37 5 5 5 5 1 5 5 2 Fig 5 11 A 3D contour map made using Type 7752 mapping software CHAPTER 5 Viewing Results 65 Exporting Post processing and Reporting Exporting Measurement Partner Suite BZ 5503 is used for communication between your PC and the analyzer Connect the analyzer to your PC using the supplied USB Cable AO 1476 Use this software to e Transfer measurement data to your PC e View data e Organise data on the analyzer e Upgrade software on the analyzer e Install software licenses on the analyzer Using this software measurements on the analyzer can be controlled from your PC Data transferred to the PC are organised in Archives where data can then be viewed Sound Intensity Data in the archives can be exported to e Microsoft Excel for further post processing and reporting e An XML file for post processing e PULSE Noise Source Identification software Type 7752 for mapping and sound power calculation Post processing and Reporting The software is further enhanced by Br el amp Kj r s
79. f the field check is not stored together with a job Tutorials Description of the Measurement and Result Displays The display views are divided into e Measurement displays for usage during measurement e Result displays for studying the results The Measurement displays are dependant on the SI Task selected in the upper right corner of the screen For SI Task S Pwr sound power mapping the available Measurement displays consist of e Surface Displays measurements in segments on a surface The segments are coloured in accordance with the measurement state e Spectrum Displays the measured spectra during the measurement For SI Task Temp Variability temporal variability the available Measurement display is e Spectrum Displays the Temporal Variability Spectrum and setting for the averaging time For SI Task Compass the available Measurement display is e Compass Useful for noise source location When opening a Sound Intensity template or project one of the measurement views will be displayed The Result displays consists of e Total Displays results from the surfaces either as a list or as numbers in a box for Total Surface Type Box only e Surface Displays measurement results as numbers in the segments or as Curve or Contour maps e Spectrum Displays measurement results The Result Displays are accessed from a link on the Measurement displays for SI Task S Pwr Examples of the various displays a
80. f the measured value 18 Segment Segment selection arrows and selected segment 19 Standard Indicates the selected standard CHAPTER 5 Viewing Results 57 5 1 2 Surface Fig 5 2 Results Surface display ad o o o o Tot Power A 55 6 dB j 1 Surface selection This selection determines the displayed surface 2 Main spectrum measurement parameter selection This selection determines the data displayed by the main frequency bar graph section 5 1 1 items 3 and 14 and displayed in the selected segment 3 Spectrum frequency cursor Selects the frequency displayed in item 15 of section 5 1 1 4 Y axis Tap on the y axis to hide show the grid hide show maxima on Curve and Contour maps and hide show cursor 5 Segments Smileys Quality indicators offering hints and guidance Time averaged value the presence and detail of the data depend on the grid resolution see section 4 2 2 Grid Tap on the segment to Select the segment Exclude Include the segment in the measurement process and calculations for the Surface parameters Copy the data in the segment to the clipboard Cut the data in the segment to the clipboard Paste the data from the clipboard to the segment Delete the segment If you have recorded the signal during the measurement Signal Recording Option BZ 7226 required you can play back the signal to the headphone output 6 Camera icon Tap camera icon to incorporate images
81. ff Field unif Rep limit Fld uni lim Ext noise Conv idx Con idx lim Fes T ievalie Segment Surface Total General result parameters Power A Surf Power A Tot Power A Start time Intensity A Surf Intensity A Tot Intensity A Stop time Pressure A Surf Pressure A Tot Pressure A Overload p I index A Surf p l index A Tot p l index A Time remaining Power Z Surf Power Z Tot Power Z Intensity Z Surf Intensity Z Tot Intensity Z Pressure Z Surf Pressure Z Tot Pressure Z p l index Z Surf p l index Z Tot p l index Z Field uniform A 64 Sound Intensity Software BZ 7233 User Manual 5 3 5 4 5 4 1 Fig 5 9 Project line Fig 5 10 Information pop up Validation There are Quality Indicators for each frequency band in each spectrum These include letters and smileys see Table 4 5 Creating New Projects Based on Recalled Projects Recall Project Press Reset Type 2270 G will start up in the most recent template Earlier projects can be recalled by tapping the project line see Fig 5 9 Choose the project you want and tap OPEN The project will then be re created allowing you to study it in detail as described in previous pages SOUND INTENSITY S Pwr You can continue your measurement and if you make a new calibration it will automatically be used for the new data The data already measured will not be affected To create a new empty project with identical s
82. h means that the smileys on the individual segments do not affect the total surface Fig 3 32 Result spectrum with smileys 90 50 25 63 250 ik 25 4k 10k AZ The Tot Pwr A parameter is the sum of the sound power from the individual segments 36 Sound Intensity Software BZ 7233 User Manual If there is a problem with the Convergence index failed smiley according to step 13 double N and remeasure by 14 Tap gt Setup gt Surface and select Rows N 2 Columns N 2 or Double no of to bring up the pop up dialog shown in Fig 3 33 Fig 3 33 Left Pop up dialog Right Adjust setting options d or to double the number and f re use the Surf N as Surf N 2 O Adjust setting O Double number of Rows B Double number of Columns f ooy Surf N 2 2 Rows 4 Columns Surf N 2 Rows 8 Columns Segment Height Segment Width 15 Place the check in the checkbox for Double number of Columns and tap OK to bring up the dialog in Fig 3 33 Right and tap OK to confirm Rows will remain the same but the N 2 value and N value for Columns will be set to 4 and 8 respectively All surface dimensions are now set 16 Repeat the measurement process until the measurement is satisfactory See section 6 16 4 for more information on measuring with this standard 3 4 6 Images With Type 2270 G turned on and Sound Intensity template selected 1 Navigate to the Surface tab 2 Tap on Ej at the bottom left of the Surface
83. ht line approximation to the pressure gradient by taking the difference in pressure and dividing by the distance between them This is called a finite difference approximation The Intensity Calculation The pressure gradient signal must now be integrated to give the particle velocity The estimate of particle velocity is made at a position in the acoustic centre of the probe between the two microphones The pressure is also approximated at this point by taking the mean pressure of the two microphones The mean pressure and particle velocity signals are then multiplied together and time averaging gives the intensity The Measuring System A sound intensity analyzing system consists of a probe and an analyzer The probe simply measures the pressure at the two microphones The analyzer does the necessary integration and calculations to find the sound intensity Fig 6 3 Fig 6 3 Sound Intensity Software BZ 7233 User Manual Block diagram for sound level meter with programmable phase correction network used for improving the residual pressure intensity index 6 7 1 Fig 6 4 Theoretical sound intensity directional characteristics for a sound intensity probe at low frequencies The acoustic centre between the microphones is held at the centre of the curve as the probe is rotated 360 degrees The Briiel amp Kj r probe has two microphones mounted face to face with a solid spacer in between This arrangement has been
84. ic for recording during the measurement Recording Quality High 20 kHz Medium 10 kHz Fair 6 6 kHz or Low 3 3 kHz in accordance with your needs NOTE High quality requires more disk space than low quality see details in Specifications Resolution 16 or 24 bit 3 3 3 3 1 CHAPTER 3 Setting up the Analyzer 13 NOTE 24 bit at High 20 kHz recording quality is not available for hardware versions 3 11 Set Output Socket Signal Source Off Intensity AF Intensity CF Intensity ZF or Generator If Generator is selected Generator settings will be available Lowest Level 0 V only availible if Source is set to Intensity AF CF or ZF From 20 to 160 dB 12 Set Headphone Signal Aural Feedback Off or On Aural Feedback Gain Enter the or dB for headphone volume 13 Set Generator Noise Type White or Pink Levelfre 1 V From 80 0 to 0 0 use number pad or the arrows up down Bottom Frequency Incrementally from 50 Hz to 10 kHz Top Frequency Incrementally from 50 Hz to 10 kHz 14 To exit the screen tap the Close icon E Calibration Using Type 4297 for Sound Pressure and Phase Calibration To calibrate the microphone pair using Sound Intensity Calibrator Type 4297 1 Place the calibrator on a clean flat surface Lift the upper half to a near vertical position as shown in Fig 3 6 to open the unit lift the black handle into the vertical position
85. ig 5 5 None x Results Total display Disk milk m map E List view Tari c N Surface Spectrum ad 19 42 06 The Total display lists the surfaces defined in the project Fig 5 5 one reading from each surface Use the check box to include exclude the entire surface from the calculation of the total power If you have set the Total Surface Type to a Box then in addition to the list of the surfaces you can select Number instead of List This will display the numbers in an exploded view of the box as in Fig 5 6 Fig 5 6 Results Total display Number view Spectrum 19 46 09 CHAPTER 5 Viewing Results 61 5 2 Examine Results 1 Select which spectra to view by tapping the parameter fields in the two lines above the spectrum display These lines also include readouts of the spectrum values highlighted by the spectrum cursor Tap on the spectrum at the frequency of interest or just tap anywhere in the spectrum area and then move the cursor to the position of interest using the left and right arrow pushbuttons To the right of the spectrum two total bars of the same parameters are also displayed The totals A and Z of the spectra are calculated from the frequency bands excluding the Excluded bands 2 Scale the Y axis left hand vertical scale of the graphical display by tapping on the scale and accessing the drop down menu see Fig 5 7 You can also select the spectrum cursor and press the Accept v pushb
86. ilable For ISO 9614 2 and ECMA 160 the measurement supports two scans per segment with repeatability check Manual Controls Reset Start Pause Back erase Continue and Store the measurement manually Measurement Mode Manual or Automatic Automatic Save option in Automatic mode Back Erase It is possible to erase backwards to the latest pause or to erase the latest scan when using ISO 9614 2 and ECMA 160 standards Aural Feedback Periodic sound signal to earphones to assist your measurement process SIGNAL MONITORING Headphone Output Can be set to output the input mean pressure signal the aural feedback signal or both to be monitored with headphones earphones Gain Adjustment 60 dB to 60 dB Output Socket Can be set to output the Intensity AF CF or ZF broadband level as a voltage between 4 47 V and 4 47 V Gain is 20 dB V Lowest level 0 V can be set INTERNAL GENERATOR Built in pseudo random noise generator Spectrum Selectable between Pink and White Crest Factor Pink Noise 4 4 13 dB White Noise 3 6 11 dB Bandwidth Selectable e Lower Limit 50 Hz 1 3 oct or 63 Hz oct e Upper Limit 10 kHz 1 3 oct or 8 kHz oct Output Level Independent of bandwidth e Max 1 Vrms 0 dB e Gain Adjustment 60 to 0 dB When bandwidth is changed the level for all bands is automatically adjusted to comply with the set output level Repetition Period 175 s Output Connector Output Socket SURF
87. ill improve the p RI index with 6 2 dB and the dynamic range at low frequencies with 12 dB but the cost is that the upper limit of the frequency ranges is reduced to 1 25 kHz Using Sound Intensity to Determine Sound Power The use of sound intensity rather than sound pressure to determine sound power means that measurements can be made on site with steady background noise and in the near field of machines It is above all a simple technique The sound power is the average normal intensity over a surface enclosing the source multiplied by the surface area First we need to define this hypothetical surface 9703808 We can choose any enclosing surface as long as no other sources or sinks absorbers of sound are present within the surface The floor is assumed to reflect all the power and so need not be included in the measuring surface The surface may in theory be any distance from the source Spatial Averaging After a surface has been defined we need to spatially average the intensity values measured normal to the surface Note that the surface can be defined with a physical grid or just as distances from reference points To obtain an average intensity value from each surface one of two spatial averaging techniques can be used CHAPTER 6 Theory and Practice 85 6 14 1 Scanning the Surface With a suitable speed the probe is simply scanned over the surface as if the surface were being painted This gives a single value s
88. ing Type 3541 for Sound Pressure and Phase Calibration For full details on the use of this calibrator please refer to Sound Intensity Calibrator Type 3541 User Manual BE 1024 12 or Sound Intensity Calibrator Type 3541 A User Manual BE 1024 version 13 or later NOTE Type 3541 A does not support phase calibration because it does not contain Sound Source ZI 0055 Sound Pressure Level Calibration To calibrate the sound pressure sensitivity of the microphone channels 1 Switch on the Analyzer and select Sound Intensity Project Template 2 Ensure that the Analyzer is properly set up for calibration with the calibrator to be used a Tap and select Setup b Expand Input by tapping it and ensure that the Input line reads Top Socket and that the Spacer line reads 12 mm c Tap and select Transducers CHAPTER 3 Setting up the Analyzer 19 If the transducers are not in the system see section 3 2 step 5 Set Input for instructions on entering a new microphone pair 3 Tap and select Calibration The Calibration screen will appear Fig 3 9 4 On the Details tab a Tap Calibrator select 3541 b Tap Calibration level and enter the sound pressure level from the Type 3541 calibration chart Type 2270 will automatically correct the calibration level for the ambient pressure during the calibration 5 On the Level tab a Tap Ambient Temperature and enter the current temperature NOTE You can set temperature to Celsi
89. ion arrows and selected segment Grid To set up the grid tap HBH Setup and then Surface and fill in the parameters The grid can be set up in different configurations for different uses For more information on setting up the grid see section 3 2 step 9 Set Surface The view of the surface is automatically adjusted for optimum use of the display area The grid is displayed to visualize the area of each segment Measurements per segment are either scanned to cover the area of the segment or measured at the centre of each segment not at the intersection of the grid lines The segments are numbered in a row column system with columns on the horizontal axis and rows on the vertical axis The segment in the lower left corner is at Row 1 R1 and Column 1 C1 Tap on an individual segment and select Exclude or Include from the drop down list to remove it from or include it back into the measurement Tap on the Row axis Y axis and select Hide Grid or Show Grid when hidden to hide or show the grid and to select the transparency of the colored segments available if there is a grid superimposed on an image a 4 2 3 Fig 4 6 Image options Sound Intensity Software BZ 7233 User Manual The amount of detail presented in the segments depends on the space available from 2 decimal places to set a default number of decimal places tap gt Preferences gt Display Settings gt Number of Decimal Places and then select 7
90. it for it to finish Phase Calibration and Pressure Residual Intensity Index Verification Phase calibration and pressure residual intensity index verification are part of the complete calibration process and should follow after sound pressure level calibration however they can also be performed individually If calibrating and verifying phase by itself perform steps 1 through 5 and then continue from step 9 NOTE Minimise vibrations at your work surface equipment during calibration as vibrations will falsely affect readings 9 Tap on the Phase tab at the bottom of the screen and the Phase calibration screen will appear Fig 3 11 18 Sound Intensity Software BZ 7233 User Manual Fig 3 11 Phase Calibration screen dB 25Hz 3 0 dB 90 50 10 J u aiic fnals o ANNUAL UAN L INAN 63 250 1k 4k 10k AZ 10 Tap Calibrate and wait for it to finish NOTE Tapping Calibrate includes the verification process but verification can be performed individually To do so tap Verify and let the verification continue for 2 minutes and press Stop Verify 11 Tap Yes to accept the new calibration and verification There should be no yellow smileys 12 Turn off the calibrator remove the probe insert the protection plug and close the calibrator NOTE The frequency range for the calibrators does not include the 8 and 10 kHz bands Results shown from these bands are extrapolated from the 6 3 kHz band 3 3 2 Us
91. l a a aa a a a a i Ean 115 A 8 Headphone Signal ccccceccceeeeeceeeeeeeeeeeeeeeeeeeeeeeeceeseeeeeeeceeeesseeesessneeees 116 AQ Generato ernen oii a cies E Naa E A ec a EES 116 APPENDIX B Measurement and Calculated Parameters s sssssssssssessessseeeseseees 117 B 1 Measurement Parameters ccccccccsssssccccccceceeeesseeeceeeesseeeeeeeeeeessseaeeeeeeeeees 117 B 2 Calculated Parameters 2 ccccccccccccccccccccccccceeeeeceeeeeeeeeeeeeceeeceeeceeeeeeeeeeeeeess 117 INDEX sists steatecocwatwcteudialddacleeds dus wovsteieuccsdlaadeiaildlwcdecuuwesuue sy sick cluetucwelebninesesaoloancdys 121 Chapter 1 1 1 1 2 1 2 1 Introduction Welcome Sound Intensity Software BZ 7233 is one of the many application packages available for Hand held Analyzer Type 2270 If you are newcomer to Hand held Analyzer Type 2270 you are strongly advised to study the User Manual for Hand held Analyzers Types 2250 and 2270 BE 1713 before reading this manual Studying the User Manual for Hand held Analyzers Types 2250 and 2270 will enable a better understanding of the platform concept and how the BZ 7233 application fits into the portfolio of available options You will also become familiar with some terms used in this manual that apply to Type 2270 in general This manual details Type 2270 for sound intensity measurements how to measure sound intensity and how to evaluate results Anything not pertaini
92. mends the use of some of the 26 data quality indicators defined in the standard The most important indicators are e D53 p I index e D52 Pressure residual intensity index minus D53 e D21 Similar to extraneous noise The following table outlines the requirements of the standard in the first column and provides the means to fulfil these requirements using the Type 2270 Hand held Sound Intensity System Required by Standard 2270 Solution Calibration The instrument including the probe shall comply with ANSI S1 40 1984 Make Pressure and Phase Calibration Make a pressure calibration of the microphones using calibrators Type 4197 3541 3541 A or 4231 Make a phase calibration using calibrators Type 4197 or 3541 Make a phase verification and measurement of the pressure residual intensity index using calibrators Type 4197 or 3541 If non compliant Yellow smiley IEC61043 Compliance failed Field Check e Measure the intensity level at the same point two times one of the times with the probe reversed The difference at the band with the maximum level shall be less than a frequency dependent limit and the values shall have opposite directions Use Field Check Perform the built in Field Check procedure If non compliant Yellow smiley for Field Check failed Detailed view of difference and limit available Stationary Noise Source Check No method given Use Temporal Vari
93. mismatch causes a small phase difference between the two signals which the analyzer interprets as intensity along the spacer The detected intensity can be likened to a noise floor below which measurements cannot be made This intensity floor is CHAPTER 6 Theory and Practice 75 not fixed it varies with the pressure level However the difference between the pressure and the intensity level when the same signal is fed to both channels is fixed The difference is defined as the pressure residual intensity index p RI index The international standard for sound intensity instruments IEC 61043 sets minimum requirements for the instruments p RI index 6 11 Dynamic Capability The dynamic capability of the system is the p RI index minus the bias error factor The bias error factor is dependant on the sound power standard used for example 7 dB for 1 dB accuracy for survey and 10 dB for 0 5 dB for precision and engineering The dynamic capability of the system p RI index bias error factor can be compared directly with the p I index of the measurement to determine if it is within the required accuracy 6 12 Measurement Limitations This section discusses in detail how frequency range pressure residual intensity index and dynamic range limitations arise and how physics limit these parameters The capability of Sound Intensity System Type 2270 G to extend the usable frequency range and pressure residual intensity index and how th
94. nd international standards and requirements 4 Sound Intensity Software BZ 7233 User Manual 2 2 Type 2270 G Overview Hand held Sound Intensity System Type 2270 G is a powerful combination of Hand held Analyzer Type 2270 Sound Intensity Software BZ 7233 and Sound Intensity Probe Kit Type 3654 and enables intensity measurements for noise source location and sound power calculations Automatic measurement guidance and aural feedback during measurements allow smooth scans of the area under investigation The system also provides on the spot analyses of sound intensity spectra and calculation of sound power Results can be exported via Measure ment Partner Suite BZ 5503 to Excel for further calculation and reporting or to PULSE Noise Source Identification Type 7752 for noise contour mapping The system is part of the Type 2270 hand held platform which has a vast range of sound and vibration analysis applica tions Fig 2 1 Hand held Sound Intensity System Type 2270 G 100114 Fig 2 2 CHAPTER 2 Concept and Contents of Type 2270 G Hand held Sound Intensity System Type 2270 G included items m KE 0458 Carrying Case UA 0781 Ellipsoidal Windscreen QA 0236 Tape Measure 4197 Sound Intensity Microphone Pair 2 DP 0888 HT 0015 BZ 7233 Intensity Adaptor Earphones Sound Intensity for 4231 Software 10 pin 10 pin 10 pin 10 pin a 2270 Hand held Analyzer 2683 UA
95. nd wait for it to finish 14 Remove the calibrator from the microphone 15 Switch off the calibrator or wait for it to stop before closing the flap on its case 3 3 4 Field Check To check the instrumentation for proper operation prior to a series of measurements perform a field check as is recommended by the supported standards 1 On the Calibration screen tap the Check tab 2 Place the intensity probe on the measurement plane with the axis oriented normal to the surface The probe should be placed at a location where the intensity is higher than the surface average 3 Tap Start First Pass to begin the measurement 4 Watch the spectrum and wait for it to stabilise at least 20 s then tap Stop First Pass 5 Note the location of the spacer and rotate the intensity probe 180 so that the probe is pointing in the opposite direction while keeping the spacer in the same position as during the first measurement 6 Tap Start Second Pass and wait for the measurement to finish the second measurement will run the same number of seconds as the first measurement or tap Stop Second Pass to end the measurement early 3 4 3 4 1 CHAPTER 3 Setting up the Analyzer 23 The cursor will automatically be set to the frequency band with the highest level which is checked against the limit NOTE Mounting the intensity probe on a stand makes it much easier to maintain the same spacer position when rotating the probe The result o
96. nes which transducer is currently transducers connected to the Hand held Analyzer and once defined in the selected the hardware of the analyzer will be transducer automatically set up to fit the transducer database You should select a Part 2 microphone from a Microphone Pair This parameter is part of the instrument setup and is common to all setups It can also be set from the Transducers option of the Main Menu Windscreen None Select Windscreen Correction if you Correction Ch 2 UA 1070 have mounted a windscreen on the Sound Intensity Probe A 2 Standard Standard Values Comment Standards None This setting determines the measurement procedure sound power ISO 9614 1 calculation and display of field indicators ISO 9614 2 See details of the standards in section 6 16 ANSI 12 12 ECMA 160 Grade of Precision This setting stipulates the accuracy of the Sound Power calculation Accuracy Engineering Survey If you follow the chosen standard and there are no smileys on the result expect the following precision of the sound power calculation e Precision 1 2 dB depending on frequency Engineering 1 5 3 dB depending on frequency e Survey 4 dB Check of Dynamic Capability uses this setting e Precision bias error factor 10 dB e Engineering bias error factor 10 dB e Survey bias error factor 7 dB A 3 Bandwidth APPENDIX A Setup Parameters 113 Parameter Values Comment Bandwidth 1 1
97. nese People s Republic of China Chinese Taiwan Croatian Czech Danish English Flemish French German Hungarian Japanese Italian Korean Polish Portuguese Romanian Russian Serbian Slovenian Spanish Swedish and Turkish HELP Concise context sensitive help in English PC REQUIREMENT Operating System Windows 7 or XP both in 32 bit or 64 bit versions Recommended PC Intel Core 2 Duo Microsoft NET 4 0 2 GB of memory Sound card DVD drive Atleast one available USB port CHAPTER 7 Specifications Compliance with Standards 111 CEB Ox The CE marking is the manufacturer s declaration that the product meets the requirements of the applicable EU directives RCM mark indicates compliance with applicable ACMA technical standards that is for telecommunications radio communications EMC and EME China RoHS mark indicates compliance with administrative measures on the control of e pollution caused by electronic information products according to the Ministry of Information Industries of the People s Republic of China WEEE mark indicates compliance with the EU WEEE Directive Safety EN IEC 61010 1 ANSI UL 61010 1 and CSA C22 2 No 1010 1 Safety requirements for electrical equipment for measurement control and laboratory use EMC Emission EN IEC 61000 6 3 Generic emission standard for residential commercial and light industrial environments EN IEC 613
98. ng to BZ 7233 will be found in the User Manual for Hand held Analyzers Types 2250 and 2270 BE 1713 This manual assumes that you are familiar with the concepts of measuring sound using a microphone and some form of sound level meter analyzer How to Use this Manual Conventions Used in this Manual Instructions and descriptions that refer to Type 2270 pushbuttons are shown with the pushbutton icons as seen on the instrument Icons Buttons and Tabs Used on the Screen Indicated by bold type face for example tap the Main Menu icon Parameter Text Appearing on the Screen Parameters instructions and descriptions appearing on the screen are indicated by italics for example Measurement Mode 2 1 2 2 1 2 3 Sound Intensity Software BZ 7233 User Manual Path Denotations Indicated by capitals for example SETUP BZ7222 Menu Screen Navigation Indicated by italics for example Setup gt Frequency Settings gt BB Peak Beginner Users of Acoustic Measurement Equipment Before you read the rest of this manual read Briiel amp Kj r s primer on Measuring Sound The Primer will give you a basic idea of acoustic measurements It can be found on the www bksv com Web site by typing Primer in the search window The Web site also contains other information you might find useful To best understand the concepts and terms related to sound intensity it is also recommended to read Chapter 6 Further information
99. nt measurements might be ignored if the influence on the total is negligible Also the sound pressure measurements are only used to test the quality of the sound intensity measurements They are not used in the sound power calculation If they give underrange indications it does not necessarily disqualify the resulting sound power The underrange indication is a good tool to assess if a measurement is approaching the lower limit of the dynamic range Nevertheless there is a gray zone where you have to make further investigations before drawing any conclusions as to the quality of your measurements These further investigations could consist of taking serials of sound intensity measurements at critical points and observing the spread of the measurements and experimenting with the distance to the sound source in these points 84 Sound Intensity Software BZ 7233 User Manual 6 12 7 6 13 Fig 6 13 Hypothetical box used as the surface surrounding a noise source 6 14 Conclusion Sound Intensity System Type 2270 G is typically able to measure sound intensity with a p I index greater than 10 dB in the frequency range of 50 Hz to 10 kHz using a 12 mm spacer This is due to the unique enhancements that Sound Intensity System Type 2270 G offers At the same time the Sound Intensity System Type 2270 G also makes it easier to check if a measurement approaches the lower limit of the dynamic range The 50mm spacer can still be used It w
100. oclave The frequency analysis is either 1 1 octave or 1 3 oclave 1 3 octave A 4 Measurement Control Measurement Mode Preset Time Segment Order Auto Save Parameter Values Comment SI Task Sound Power Mapping Choose Sound Power Mapping for sound power Temporal Variability calculations and for noise mapping Compass Choose Temporal Variability for testing whether the sound field is stationary or not Choose Compass for on line noise source location Measurement Mode Manual Determines whether the measurement is under Automatic Manual control fully controlled by the Reset and Start Pause pushbuttons or Automatic control start of measurement controlled by the Reset and Start Pause pushbuttons end of measurement automatically controlled by the instrument when preset time has elapsed Preset Time 00 00 01 to Fixes the duration of a measurement from 24 00 00 start to automatic stop in hours minutes and seconds Any pauses made during the measurement via the Start Pause pushbutton are not counted in the preset time Segment Order 16 combinations Determines which segment to select for the next measurement The segment is selected when a measurement has been saved Choose the combination that suits your measurement sequence Automatic Save Off On Choose On to save the measurement automatically when the preset time has elapsed and the measurement pauses The Segment Selector automatically inc
101. ompensation lower low frequency limit can be achieved while retaining the high frequency limit This is exactly what Sound Intensity System Type 2270 G and Sound Intensity Calibrator Type 4297 can do In Calibrator Type 4297 both microphones are fed the same acoustical pink noise signal With this signal Type 2270 measures the pressure residual intensity index and from the pressure residual intensity index calculates the coefficients for the phase correction networks in the two channels Fig 6 3 To improve accuracy this process is repeated a number of times The phase correction networks correct for phase errors at both low and high frequencies A typical improvement of the pressure residual intensity index can be seen in Fig 6 11 Note that not only is pressure residual intensity improved at low frequencies but it is also improved in the rest of the frequency range giving an improved dynamic capability at all frequencies Fig 6 11 Left Typical Pressure residual intensity index without any phase calibration shown with minimum values required by IEC 61043 PT ill Right 10 10 intensity index after phase 10k AZ 25 6 1k 4k 10k az calibration EE Time 6 12 5 Dynamic Range of Measurements The dynamic range of the measurement is the range of levels that can be measured without errors greater than a certain limit not to be confused with the dynamic capability defined in section 6 11 At high levels the dynamic range
102. or 2 to no decimals and in extreme cases not displayed at all Quality indicators for the values are displayed as smileys see Table 4 6 Depending on the space available Smileys will either be large small or not present Images The grid in surface view can be superimposed on an image made by Type 2270 The image for display can be selected among the images made for the project The images are listed on the Annotations screen To re use images in a new project see section 5 4 1 Tap E to select or adjust the image If no image has been selected before for the project then pressing the photo icon will just open the Annotations screen for selection of the image If no image is in the list you will have to make one first 1 Tap on the name of an image in the list and choose Select for Surface to open the image for selecting the part of the image you want displayed on the surface 2 Tap on the image and drag the stylus across the part of the image that will be measured 3 Tap EJ to accept the selection and close the Annotations display The selected area is displayed behind the grid NOTE The image is turned into a black and white image for better readability of the information superimposed on the image Tapping after the image has been selected brings up the options menu shown in Fig 4 6 e Adjust Selection reopens the image to re select the grid area on the image e Select Image returns to the Annotations tab to select a
103. or to double the number and re use the Surf N as Surf N 2 Adjust setting O Double number of Rows O Double number of Columns 34 Sound Intensity Software BZ 7233 User Manual d e Fig 3 30 Left Pop up dialog Right Adjust setting options To set the N value to double Columns tap the parameter to the right of Double no of Columns to bring up the pop up dialog shown in Fig 3 30 place the check in the checkbox for Adjust setting and tap OK Select Columns The N value for Columns will be set to 4 or to double the number and re use the Surf N as Surf N 2 Adjust setting O Double number of Rows O Double number of Columns All surface dimensions are now set 6 Perform a measurement at each segment of the two surfaces 7 Position the probe at the center of the segment Place the probe on the measurement plane with the axis oriented normal to the surface Let the curved part of the probe point towards the plane such that the acoustical centre of the probe the middle of the spacer not the tip of the probe is bisected by the plane NOTE As an alternative to this meathod scanning can be used 8 Press 4 and measure for the full time period that was stipulated in Setup When the specified time period has elapsed the measurement will automatically pause For the required time period see section 6 16 4 9 Examine the spectrum a b If the result is satisfactory press amp
104. ource were then moved outside the surface and we tried to find the sound power we would measure zero We will always measure some energy flowing in on a part of the surface But the energy will flow out on other parts of the surface and so the contribution to the sound power radiated from the surface will be zero Background noise can be regarded as sources outside the measurement surface and will have no effect on the measured sound power of the source in theory For this to be true the background noise level must not vary significantly with time If this condition is met the noise is said to be stationary NOTE With a long enough averaging time small random fluctuations in level will not matter A further condition is that there must be no absorption within the surface Otherwise some background noise will not flow out of the surface again In practice this means that sound power can be measured to an accuracy of 1 dB from sources as much as 10 dB lower than the background noise If background noise is a problem then choosing a smaller measurement surface will improve the signal to noise ratio 86 Sound Intensity Software BZ 7233 User Manual Fig 6 14 The calculated sound power is only related to the energy generated inside the enclosed surface Source enclosed by measurement surface Ne Nas es oe ws Power W Watts lt NS 1 Source not enclosed by measurement surface Power W Watts CHAPTER 6
105. oximated in a reverberant room Although the net intensity is zero there is a theoretical relationship which relates the pressure in the room to the one sided intensity 1 This is the intensity in one direction ignoring the equal and opposite component One sided intensity cannot be measured by a sound intensity analyzer but it is nevertheless a useful quantity By measuring pressure we can use the relationship between pressure and one sided intensity to find the sound power This is described in ISO 3741 Active and Reactive Sound Fields Sound propagation involves energy flow but there can still be a sound pressure even when there is no propagation An active field is one where there is energy flow In a purely reactive field there is no net energy flow That is energy may be travelling outward at any instant but it will always be returned at a later instant The energy is stored as if in a spring Hence the net intensity is zero In general a sound field will have both active and reactive components 6 4 4 6 5 6 6 6 6 1 Sound Intensity Software BZ 7233 User Manual Pressure measurements for sound power in fields that are not well defined can be unreliable since the reactive part is unrelated to the power radiated We can however measure sound intensity Since sound intensity describes energy flow there will be no contribution from the reactive component of the field The Near Field of a Source In the region ver
106. patial average intensity for the surface Multiplying by the area gives the sound power from this surface Then the sound power contributions from all the surfaces are added to give the total sound power 6 14 2 Discrete Point Averaging Another method of averaging is to divide the surface into small segments and measure the sound intensity at discrete points in each segment The measuring points are frequently defined by a grid This can be a frame with string or wire although a ruler or tape measure can also be used The results are averaged and multiplied by the surface area to find the sound power from the surface Neither method is best for all applications and in some cases both methods may be useful Because the scanning technique is mathematically a better approximation to the continuous space integral it is often more accurate and fast But care needs to be taken to sweep the probe at a constant rate and to cover the surface equally The discrete point method however is often more repeatable 6 15 What about Background Noise One of the main advantages of the intensity method of sound power determination is that high levels of steady background noise are not important Let us imagine a surface in space any closed volume will do If a sound source is present within the closed surface then we can measure the average intensity over the surface and multiply by the area to find the total sound power radiated by the source If the s
107. pensated sound intensity directional characteristics for Microphone Pair Type 4197 anda 12mm spacer at 50 Hz and 3 15 4 5 6 3 8 and 10 kHz 1 3 octave bands measured with pink noise Fig 6 9 Directional characteristics from Fig 6 8 compensated with optimized frequency response for Microphone Pair Type 4197 This compensation is done automatically by Type 2270 G Sound Intensity System CHAPTER 6 Theory and Practice 79 6 12 3 The Low Frequency Limit At low frequencies there will be only a small difference between the signals from the two microphones Fig 6 10 The measurements will therefore be more sensitive to self generated noise and phase mismatch errors in the measurement equipment Fig 6 10 Free field phase change over spacer distance The phase change over the spacer is very small at low frequencies 60 Phase Change I 1 Phase Change 860806 1 These problems can be reduced by using a longer spacer between the microphones but as stated in section 6 12 1 this will reduce the high frequency limit This section further examines phase mismatch errors the effects of self generated noise will be examined in section 6 12 5 In Fig 6 10 the same sound signal arrives at the two microphones with a small delay that is used to calculate the velocity of the sound propagation Because there are translations between delay phase and pressure intensity in
108. point measurements Frequency Range 31 5 Hz to 8 kHz in 1 1l octaves and 25 Hz to 10 kHz in 1 3 octaves Initial Test 1 Calibrate the intensity system as described in section 3 3 2 Check the instrumentation for proper operation by performing a field check as described in section 3 3 4 3 The sound field shall be stationary Briiel amp Kj r recommends checking whether or not the sound field is stationary by measuring the temporal variability as described in section 4 6 The Measurement Method 1 Define a number of measurement surfaces as planes of at least 3 x 3 segments around the interesting parts of the test source 2 Define the dimensions of the surfaces 3 Capture an image for each surface and overlay them on the surfaces 4 Use the image and grid as a guideline for positioning the probe at the center of the segment with the probe pointing towards the source and with the acoustic center of the probe bisected by the surface 5 Perform a measurement at each segment 6 Evaluate a The dynamic capability compared to the p I index of the measurement b The amount of extraneous noise if your surface encapsulates the device under test 7 The sound power is automatically calculated per segment per surface and for the total surface 8 Views of colored contours or contour level curves are available The pressure intensity p I index and sound power are calculated in Type 2270 per segment per surface and for the
109. pt The connection is password protected Two levels of protection e Guest level for viewing only e Administrator level for viewing and full control of the instrument Software Specifications Signal Recording Option BZ 7226 Signal Recording Option BZ 7226 is enabled with a separate license It works with all the software for Type 2250 2270 For data storage Signal Recording requires e SD Card All hardware versions e CF Card Hardware versions 1 3 e USB Memory Stick Hardware version 4 RECORDED SIGNAL Z weighted signal from the two microphones SAMPLING RATE AND PRE RECORDING Sampling Recording Memory Memory Rate Quality KB s KB s kHz kHz 16 bit 24 bit 8 Low 32 48 3 3 16 Fair 64 96 6 6 24 Medium 96 144 10 48 High 192 288 20 PLAYBACK Playback of signal recordings can be listened to using the earphone headphones connected to the headphone socket RECORDING FORMAT The recording format is either 24 or 16 bit wave files extension WAV attached to the data in the project Calibration information is stored in the WAV file allowing BZ 5503 and PULSE to analyse the recordings Automatic Control of Recording Start of recording when measurement is started NOTE 24 bit at High 20 kHz recording quality is not available for hardware versions 1 3 Sound Intensity Software BZ 7233 User Manual Specifications Measurement Partner Suite BZ 5503
110. r 10log X S 0 10 where p pressure of segment i p 20 uPa N number of segments I Intensity of segment i Ig 1pW m and S area of segment i a Sound Intensity Software BZ 7233 User Manual The following table outlines the requirements of the standard in the first column and provides the means to fulfil these requirements using the 2270 Hand held Sound Intensity System Required by Standard 2270 Solution Calibration e The instrument including the probe shall comply with IEC 1043 Make Pressure and Phase Calibration e Make a pressure calibration of the microphones using calibrators Type 4197 3541 3541 A or 4231 e Make a phase calibration using calibrators 4197 or 3541 e Make a phase verification and measurement of the pressure residual intensity index using calibrators 4197 or 3541 e If non compliant Yellow smiley IEC61043 Compliance failed Field Check e Measure the intensity level at the same point two times one of the times with the probe reversed The difference at the band with the maximum level shall be less than 1 5 dB and the values shall have opposite directions Use Field Check e Perform the built in Field Check procedure Calibration Check e If non compliant yellow smiley for Field Check failed Detailed view of difference and limit available Stationary Noise Source Check Chose a typical measurement position e Measure
111. re used in the tutorials and in chapters 4 and 5 24 Sound Intensity Software BZ 7233 User Manual 3 4 2 On line Noise Source Location Compass With 2270 G turned on and Sound Intensity template selected and a microphone pair set up 1 Tap the far right section of the Template line Fig 3 3 then tap Compass 2 Select the desired parameter Intens ZF or Intens AF and frequency 25 Hz 10 kHz or A or Z weighted Fig 3 15 Left i D Compass display positive 00 omni Int E lt 500Hz gt 41 4 d amp 7 Right I I So f 0 Compass display negative 30 1 15 50 43 3 Holding the microphone pair parallel with the plane of the measured surface scan the plane and observe the motion of the speaker icon on the compass display NOTE The probe should be oriented the same way as the probe presented on the Compass display either change the direction of the probe in your hand or tap the image of the probe on the Compass display which will flip the image of the display Three positions are available 1 Pointing to the left 2 probe pointing to the right and 3 probe pointing forwards When the speaker is in front of the probe the noise source is in front of the probe and the direction of the sound intensity is defined as positive indicated in Fig 3 15 Left with the white bar graph and the sign behind the dB in the readout When the speaker is behind the probe the noise source is behind and the direc
112. rease the averaging time at each position Sound Field Is Non uniform and 1 dB lt Extraneous Noise lt 3 dB Suitable for ISO 9614 1 Increase the density of measurement positions uniformly Sound Field Is Non uniform and Extraneous Noise lt 1 dB Suitable for ISO 9614 1 Increase average distance of measurement surface from source using the same number of measurement positions or increase the number of measurement positions on the same surface Underrange at Frequencies below 1 kHz Suitable for All Standards Select p gt Setup gt Input gt Range Setting gt Low Range or Increase the averaging time or Increase spacer length to 50 mm 102 Sound Intensity Software BZ 7233 User Manual Chapter 7 Unless otherwise stated values are given as typical values under Reference Environmental Conditions with nominal sensitivities Specifications Type 2270 with Sound Intensity Probe Type 3654 and Software BZ 7233 Specifications are given for Type 2270 G with software BZ 7233 installed and using Sound Intensity Probe Kit Type 3654 including 2 Microphone Pair Type 4197 and Dual Preamplifier Type 2683 Unless otherwise noted values are given under reference ambient conditions with nominal sensitivities for the microphones and preamplifiers see the Product Data for Type 3654 BP 2324 and with a 12 mm spacer Licenses for Sound Level Meter Software BZ 7222 and Sound Intensity Software BZ
113. rements to point at next segment in accordance with the Segment Order setting 114 Sound Intensity Software BZ 7233 User Manual A 5 Surface Dimensions Parameter Values Comment Surface Type Custom Choose Custom to set up a number of independent Box surfaces Choose Box to set up a box with 5 surfaces Number of Surfaces 1 to 25 Define the number of surfaces Select the surfaces one by one to define the segments of the selected surface NOTE The number of surfaces is doubled when using ANSI 12 12 Selected Surface Plane1 to Plane25 Select the surface to be defined for Name Height Width Rows and Columns NOTE Select the N 2 surfaces when using ANSI 12 12 Surface Name Text string Use this parameter to specify a name for the selected surface The name is displayed in the status panel Surface Height 0 01 to 500m Use this parameter to specify the total height of the surface The area of the surface is used for calculating the Total Sound Power from the Surface Surface Width 0 01 to 500m Use this parameter to specify the total width of the surface The area of the surface is used for calculating the Total Sound Power from the Surface Rows 1 to 15 Use this parameter to specify the number of rows you want to divide the surface into Columns 1 to 15 Use this parameter to specify the number of columns you want to divide the surface into Double no of Rows Choose to do
114. residual intensity index for the analyzer 980317 1 CALIBRATION Acoustic Individual Pressure gain calibration of the two input channels can be performed using Sound Intensity Calibrator Type 4297 Sound Intensity Calibrator Type 3541 A Sound Calibrator Type 4231 with Coupler DP 0888 or a custom calibrator Electrical Using internally generated electrical signal combined with typed in value of microphone sensitivity Calibration History Up to 20 of the latest calibrations made are listed and can be viewed on the instrument Verification Verification of the Pressure residual intensity index can be made using Sound Intensity Calibrator Type 4297 Pressure residual intensity index is stored with the calibration and on each measurement for documentation purposes and for calculating the dynamic capability Field Check A field check of the intensity measured with the probe in normal and reversed position can be performed MEASUREMENTS Spectra Simultaneous measurement of mean pressure and intensity TEMPORAL VARIABILITY Assessment of whether or not the sound field is stationary Measured in accordance with ISO 9614 1 Result stored with project MEASUREMENT CONTROL Manual or semi automatic Measurements are started manually and the user is guided through the measurement for each segment After storing the measurement for one segment the analyzer is automatically ready to measure the next segment 16 different segment sequences are ava
115. ress and listening for the Aural feedback scan the segment in an evenly paced S pattern covering equal areas in equal time for the full time period minimum 20 seconds that was stipulated in Setup When the specified time period has elapsed the measurement will automatically pause and the count indication will change from to 2 9 Press 4 and listening for the Aural feedback scan the segment in an evenly paced s pattern orthogonal to the s pattern used in step 8 covering equal areas in equal time for the full time period minimum 20 seconds that was stipulated in Setup When the specified time period has elapsed the measurement will automatically pause 10 Examine the spectrum a If the result is satisfactory press amp b Ifthe result was unsatisfactory press gt and remeasure the segment NOTE If you have Repeatability failed smileys at important frequency bands you might need to redo both scans Refer to section 6 16 6 for more hints on what to do if there is a repeatability failed or other smiley 11 Select the next surface for example Left Repeat steps 7 through 11 for the remainder of the measurement 12 Tap Result gt and select the Spectrum tab and set the Spectrum Parameters to Power A and Tot Pwr A If the A total reading in Tot Pwr A does not have a smiley there are no warnings for the CHAPTER 3 Setting up the Analyzer 31 calculated A total However if it has a smiley you mus
116. s Setups can be locked and password protected Project Measurement data stored with the Project Template Job Projects are organised in Jobs Explorer facilities for easy management of data copy cut paste delete rename open project create job set default project name USB INTERFACE Hardware Versions 1 to 3 USB 1 1 OTG Mini B socket Hardware Version 4 USB 2 0 OTG Micro AB and USB 2 0 Standard A sockets MODEM INTERFACE Connection to Internet through GPRS EDGE HSPA modem connected through the Compact Flash slot hardware versions 1 3 e the USB Standard A Socket hardware version 4 Supports DynDNS for automatic update of IP address of host name PRINTER INTERFACE PCL printers Mobile Pro Spectrum thermal printer or Seiko DPU 8245 8445 thermal printers can be connected to USB socket COMPACT FLASH SOCKET Hardware Version 1 to 3 only Connection of CF memory card CF modem CF to serial interface CF Ethernet interface or CF WLAN interface SECURE DIGITAL SOCKET e 1 x SD socket for hardware versions 1 3 e 2 x SD sockets for hardware version 4 Connect SD and SDHC memory cards 108 Sound Intensity Software BZ 7233 User Manual LAN INTERFACE SOCKET Hardware Versions 1 to 3 Type 2270 only e Connector RJ45 MDI e Speed 10 Mbps e Protocol TCP IP Hardware Version 4 Types 2250 and 2270 Connector RJ45 Auto MDIX e Speed 100 Mbps e Protocol TCP IP TWO INPUT SOCKETS Connector Tria
117. s in Fig 5 4 The curves are interpolated from the measured values Select Contour to display a color between the curves of equal levels as in Fig 5 2 The scale to the right of Curve and Contour maps defines the colors used and the range of the displayed values Tap on the scale to zoom in or out If Auto Scale Always is set the display is auto scaled whenever the content is changed Set Auto scale to off if you want to control it yourself using Scale Up or Scale down You can also tap on the scale to set the transparency on Contour maps and set the color scale on the Curve and Contour maps CHAPTER 5 Viewing Results 59 Fig 5 3 Results Surface display 17 Curve index Tap to Zoom In Zoom Out set Auto Scale to On or Off set Transparency for the curves or set Color Scale to Multi Color or Red Blue Fig 5 4 Results Surface display iG c c2 c3 c4 c c6 Tot Power A 18 Contour index Tap to Zoom In Zoom Out set Auto Scale to On or Off set Transparency for the curves or set Color Scale to Multi Color or Red Blue The spectrum parameters and the parameters selected in the value panels are selected indepen dently of the parameters selected in the measurement displays however the selected position in the surface Row Column is aligned between the measurement and result displays as is the cursor position in the spectrum 60 Sound Intensity Software BZ 7233 User Manual 5 1 3 Total Display F
118. se icon is displayed in the status field then the measurement reverts to a stopped state after a reset i e Stopped icon W displayed with a zeroed readout If the measurement is running then the measurement will be automatically re started after the reset If there are no data to reset no unsaved data you will be asked if you want to create a new project using the current template Start Pause Pushbutton Sound Intensity Software BZ 7233 User Manual Use the Start Pause pushbutton for controlling the measurement The function of this key depends on the current measurement state standard and SI state see Table 4 1 and Table 4 1 Table 4 1 Start Pause pushbutton functions Table 4 2 Start Pause pushbutton functions for ISO 9614 2 and ECMA 160 Save Pushbutton eae Function of Next Measurement Start Pause Pushbutton State State E Stopped Start the measurement gt Running gt Running Pause the measurement Paused Paused Continue the measurement gt Running Current Wi asuremeni Function of Next Measurement Start Pause Pushbutton State State E Stopped Start scan 1 gt Running scan 1 gt Running scan 1 Pause scan 1 Paused scan 1 Paused scan 1 Start scan 2 gt Running scan 2 gt Running scan 2 Pause scan 2 Paused scan 2 Paused scan 2 No function Paused scan 2 Use the Save pushbutton Q to s
119. see section 4 2 3 a Sound Intensity Software BZ 7233 User Manual 7 Single values parameter Below the graph one single measurement parameter is displayed Tap on it to choose a parameter for your reference Refer to section 5 2 2 for details 8 Single value parameter corresponding value Refer to section 5 2 2 for details 9 X axis Columns 10 Grid See section 4 2 2 Grid 11 Averaged value Displays the time averaged value at the displayed frequency item 3 The presence and detail of the data is dependant on the grid resolution see section 4 2 2 Grid 12 Quality indicator Smiley Indicates a problem in the parameters defined by measurement parameter see item 2 segment see item 14 and spectrum cursor display see item 3 This smiley can be tapped for a display of the specific problem More smiley information is presented in Table 5 2 13 Level dBs defined by measurement parameter see item 2 segment see item 14 and spectrum cursor display see item 3 Readouts for values with a direction have a or behind the dB to indicate the direction of the measured value 14 Segment Segment selection arrows and selected segment 15 Standard Indicates the selected standard 16 Surface Type selection Select between Number Curve and Contour Select Number to display a number map as in Fig 5 2 The measured values at the selected frequency are displayed Select Curve to display curves of equal levels a
120. sing gently rotating if necessary to correctly align the LEMO connectors until it snaps into position Push the securing sleeve up and screw the sleeve into position Fig 3 2 Fig 3 2 The probe in position on the extension stem 3 1 5 3 1 6 CHAPTER 3 Setting up the Analyzer 9 970538e Mounting the Extension Stem onto the Handle Insert the probe plug into the input socket at the top of the handle Push into position and secure by turning the threaded securing sleeve Removing the Probe from the Handle or Extension Stem To remove the probe from the handle slide back the locking ring and gently pull out the probe When removing the probe from the extension stem unscrew the threaded securing sleeve slide back the locking ring and gently pull out the probe 10 Sound Intensity Software BZ 7233 User Manual 3 2 Setting up Type 2270 G To set up Type 2270 for the Sound Intensity Project Template 1 Select the SOUND INTENSITY Project Template see section 3 3 1 of Hand held Analyzers Types 2250 and 2270 User Manual for more details on templates The Project Template is displayed on the black banner at the top of the screen see Fig 3 3 If this banner does not display SOUND INTENSITY tap on the banner and select SOUND INTENSITY from the drop down menu and then select Open from the subsequent drop down menu Fig 3 3 Template line displaying UND IN YASO 9614 1 S Pwr a Template b Stan
121. spect to the other Multiplying the two signals together gives an instantaneous intensity signal varying sinusoidally about zero Therefore the time averaged intensity is zero In a diffuse field the pressure and particle velocity phase vary at random and so the net intensity is zero How is Sound Intensity Measured Finding the Particle Velocity Sound intensity is the time averaged product of the pressure and particle velocity A single microphone can measure pressure this is not a problem But measuring particle velocity is not as simple The particle velocity however can be related to the pressure gradient the rate at which the instantaneous pressure changes with distance This is done with the linearized Euler equation see Fig 6 2 With this equation it is possible to measure this pressure gradient with two closely spaced microphones and relate it to particle velocity Fig 6 2 CHAPTER 6 Theory and Practice 71 From Euler The pressure gradient is 1 720 approximated by using two YEO or dt closely spaced pressure microphones p is the density of the media 6 6 2 6 6 3 6 7 The Finite Difference Approximation oo 1 f p p dt P Ar _ Pit P2 P 3 I pv _ Pit P2 _ I al p2 p dt 980276 2 The Finite Difference Approximation The pressure gradient is a continuous function that is a smoothly changing curve With two closely spaced microphones it is possible to obtain a straig
122. spectrum parameters are calculated per surface excluding Excluded segments e Surface Sound Power Z weighted e Surface Sound Power A weighted e Surface Intensity Z weighted e Surface Intensity A weighted e Surface Mean Pressure Z weighted e Surface Mean Pressure A weighted e Surface Pressure Intensity Index e Surface Dynamic Capability The following single value parameters are calculated per surface excluding Excluded segments e Surface Sound Power Z weighted e Surface Sound Power A weighted e Surface Intensity Z weighted e Surface Intensity A weighted e Surface Mean Pressure Z weighted e Surface Mean Pressure A weighted e Surface Pressure Intensity Index Z weighted e Surface Pressure Intensity Index A weighted The following Total spectrum parameters are calculated based on all surfaces excluding Excluded segments e Total Sound Power Z weighted e Total Sound Power A weighted e Total Intensity Z weighted e Total Intensity A weighted e Total Mean Pressure Z weighted e Total Mean Pressure A weighted APPENDIX B Measurement and Calculated Parameters 119 e Total Pressure Intensity Index e Total Dynamic Capability e Extraneous Noise e Field unif Field non uniformity indicator F4 ISO 9614 1 only e Fld uni lim Limit for Field non uniformity indicator ISO 9614 1 only e Convergence Index ANSI 12 12 only e Convergence Index Limit ANSI 12 12 only The following
123. surement has a 95 confidence interval of maximum 0 7 dB In practice the object you are measuring also gives a spread in the measurements However you can conclude that if you have a greater confidence interval on your measurements some of the spread comes from the object e If there is an underrange indication at low frequencies You cannot conclude that you have a bad sound pressure measurement The sound pressure part of the curves in Fig 6 12 continues nearly flat at low frequencies so the sound pressure measurement could be good even if the sound intensity measurement is corrupted You can conclude that your sound intensity measurement has a 95 confidence interval that is greater than 0 7 dB e Ifyou have an underrange indication at high frequencies You can conclude that your sound pressure measurement has a bias error greater than 0 5 dB You cannot conclude that you have a bad sound intensity measurement The sound intensity part of the curves in Fig 6 12 continues to decrease at high frequencies so the sound intensity measurement could be good even if the sound pressure measurement is corrupted e While measuring the averaging time increases and therefore the underrange limit decreases at low frequencies You can therefore experience that a measurement starts with underrange indications at low frequencies and that they disappear after some time e For total sound power underrange indications in some segme
124. switched on On or not Notes on Aural Feedback While measuring you get a signal each second to assist you in keeping a steady scanning pace After 20 s all the signals will be set one octave higher to indicate the fulfilment of the minimum required scan time Overloads are indicated by two tones In the Compass display you will each second get a signal with the high pitch for positive direction in front of the probe and a low pitch for negative direction behind the probe of the selected frequency band Aural Feedback Gain 70 to 10 dB Use this parameter to specify the gain of the aural feedback The aural feedback can be listened to together with the signal if Listen to signal is set in Preferences Headphone Settings A 9 Generator Parameter Values Comment Noise Type Pink The type of noise from the internal generator The White bandwidth of the noise will be adjusted to the frequency range from Bottom Frequency to Top Frequency Level re 1 V 60 0 to 0 0 dB This sets the internal noise generator attenuation in dB referenced to 1 V This level stays at the set level irrespective of the frequency range Bottom Frequency 50 Hz to Top 1 1 octave 63 Hz 8 kHz Frequency 1 3 octave 50 Hz 10 kHz NOTE The settings of Bottom and Top Frequency control the bandwidth of the noise from the internal noise generator Top Frequency Bottom 1 1 octave 63 Hz 8 kHz Frequency to 1 3 octave 50 Hz 10 kHz 10 kHz
125. t Segment selection arrows and selected segment 20 Paperclip icon Click this icon to access the metadata text fields and annotations commentaries notes and images common to the project If the icon is not visible there are no metadata or annotations Use the Analyzer s Up Arrow 4 Down Arrow T pushbuttons to move the field selector to the Project line and press the Right Arrow pushbutton to reveal the Paperclip icon Press the Accept pushbutton v to access the Annotations screen and enter metadata 21 Standard When S Pwr Sound Power Mapping is selected select None ISO 9614 1 ISO 9614 2 ANSI S12 12 or ECMA 160 22 SI Task Select Pwr Sound Power Mapping Temp Variability or Compass 23 Paperclip icon Click this icon to access the metadata text fields for the current segment You can define metadata for all segments here These are saved on the template The values of the metadata can then be set per segment If the icon is not visible there are no metadata or annotations Use the Analyzer s Up Arrow 1 Down Arrow T CHAPTER 4 Measuring fs pushbuttons to move the field selector to the Segment line and press the Right Arrow pushbutton to reveal the Paperclip icon Press the Accept pushbutton y to access the Annotations screen and enter metadata 24 Additional Information while Standard Is Set to ISO 9614 2 or ECMA 160 When the standard is set to ISO 9614 2 or ECMA 160 additional stan
126. t investigate the segment spectra or surface spectra in more detail Fig 3 25 Spectrum Result tab with parameters set to Power A and Tot Pwr A so ll ANN ere uillll S 63 250 1k 4k 10k AZ 13 Examine the saved data in the segments looking for smileys in different frequencies or with A or Z weighting 14 Tap Spectrum and use the display cursor to examine different frequencies for different segments and exclude or include bands to pinpoint problems If a yellow smiley is present below a frequency band tap in the spectrum to select this band with the cursor then tap the smiley at the cursor readout to determine the cause If the dynamic capability is too low examine the p I index of the individual segments Select Dynamic C and p I index and step through the segments using Eq or gt in order to locate segments that need to be remeasured NOTE In Fig 3 21 the Tot Pwr A has no smiley which means that the smileys on the individual segments do not affect the total surface The Tot Pwr A parameter is the sum of the sound power from the individual segments 32 Sound Intensity Software BZ 7233 User Manual Fig 3 26 Result spectrum with smileys 63 k 25 250 1 4k 10k AZ See section 6 16 2 for more information on measuring with this standard 3 4 5 Sound Power Measurement Standard ANSI 12 12 With 2270 G turned on Sound Intensity template selected and a microphone pair set up an
127. the list of options The Calibration screen will appear Fig 3 9 5 On the Details tab a Tap Calibrator select 4231 6 On the Level tab a Tap Ambient Temperature and enter the current temperature NOTE You can set temperature to Celsius SJ or Fahrenheit US UK set in Preferences gt Regional Settings gt Temperature Unit b Tap Ambient Pressure and enter the current barometric pressure 7 Insert microphone pair Part2 cable B channel 2 into the Type 4231 slightly loosen the compression joints for both tubes so that the Channel 2 tube can be pushed forward and the Channel 1 tube can be pulled back and twisted out of the way see Fig 3 13 Fig 3 13 Single microphone arrangement P D a 970537e 8 Press the calibrator s On Off button you should be able to hear a faint tone then tap the Calibrate button on the Type 2270 touch screen 9 The Analyzer will prompt you to continue when Channel 2 s level has been detected 10 Remove microphone pair Part2 cable B channel 2 from the calibrator and insert it into Coupler DP 0888 11 Insert microphone pair Part1 cable A channel 1 into the other side of the coupler and insert Coupler DP 0888 into the calibrator see Fig 3 14 22 Sound Intensity Software BZ 7233 User Manual Fig 3 14 Dual microphone arrangement 12 Press the calibrator s On Off button on the calibrator listen for the tone 13 Tap Continue Calibration a
128. the segments together Calculation of Sound Power e Sound power is automatically calculated for the displayed segment surface or total surface Calculation of A total e Calculate A total from all the frequency bands but don t use bands not fulfilling criteria 1 dynamic capability and or 2 field uniformity e Uncertainty in any frequency band more than 10 dB below A total is irrelevant e Frequency bands with a sum more than 10 dB below A total may be ignored A weighted bands below 50 Hz or above 6 3 kHz should be more than 6 dB below the total value e A total is calculated on all segments surfaces and total surface using frequency bands not marked with Dynamic Capability too low or Sound Field is non uniform e Only the smileys relevant for the calculation of A total are marked on the A total e A weighted bands below 50 Hz and above 6 3 kHz checked If too high A smiley High levels outside Tot A freq range set on A total Increase accuracy In order to guarantee upper limits for uncertainties of the sound power levels determined certain actions have to be taken if criteria 1 and 2 are not fulfilled See Hints for Improving Accuracy 6 16 2 CHAPTER 6 Theory and Practice 91 ISO 9614 2 1996 E Determination of Sound Power Levels of Noise Sources using sound intensity Part 2 Measurement by Scanning ISO 9614 2 is an appropriate standard for on site determination
129. tings to Input Ch 2 NOTE 1 4 microphones will need to be individually input If the microphone pair does not appear in the list they must be defined a b c d e f g h Tap and select Transducers Tap the New Transducer icon XK and select Microphone Pair The microphone pair is then created as 4197_PJ 0 and 4197_P2 0 and automatically selected as input for Ch 1 and Ch 2 Tap on 4197_P1 0 to open it If the microphone pair is a Type 4181 pair tap on Microphone Type and select 4181 Tap Serial No and insert serial number of the microphone pair Tap 4 when finished Tap Preamplifier ID No and insert serial number of the preamplifier Tap wv when finished You should now have a screen like Fig 3 5 Fig 3 5 Transducer input screen 10 17 12 12 Sound Intensity Software BZ 7233 User Manual 6 Set Standard see section 6 16 None ISO 9614 1 ISO 9614 2 ANSI 12 12 or ECMA 160 7 Set Bandwidth Bandwidth I l octave or 1 3 octave 8 Set Measurement Control SI Task Sound Power Mapping Temp Variability or Compass Measurement Mode Manual or Automatic Preset Time Enter time Segment Order Select measurement pattern from drop down list Automatic Save Yes or No 9 Set Surface Total Surface Type Box the number or surfaces will be set to five prearranged in the Box pattern or Custom the number of surfaces can be user defined
130. tion of the sound intensity is defined as negative indicated in Fig 3 15 Right with a coloured bar graph and a sign behind the dB in the readout When the speaker icon jumps rapidly back and forth on the display the noise source is in the probe s 90 direction further information in Fig 6 4 Using Aural Feedback in the headphones aids locating the noise source relative to the probe high pitch indicates that the noise source is in front of the probe and low pitch behind CHAPTER 3 Setting up the Analyzer 25 Fig 3 16 Aural Feedback setup Signal Recording Output Socket Signal Headphone Signal Aural Feedback Aural Feedback Gail Generator Po e 15 28 16 3 4 3 Sound Power Measurement Standard None With 2270 G turned on Sound Intensity template selected and a microphone pair set up and selected see section 3 2 1 Perform calibration see section 3 3 2 Tap the far right section of the Template line Fig 3 3 then tap S Pwr Ensure that Standard is set to None 3 Set Measurement Control tap gt Setup gt Measurement Control see section 3 2 Fig 3 17 SETUP Measurement Control setup SI Task Sound Power Mapping Measurement Mode Automatic Preset Time 00 00 20 Segment Order Automatic Save Off Signal Recording I Output Socket Signal Headphone Signal 15 33 22 4 Set Surface tap gt Setup gt Surface see sections 3 2 and 4 2 2 26 So
131. ty Software BZ 7233 User Manual Fig 7 1 30 So Pressure Residual Intensity Index dB 12 mm ENHANCED PHASE MATCHING The phase matching of the sound intensity system can be enhanced using a Sound Intensity Calibrator Type 4297 HIGH FREQUENCY COMPENSATION High frequency compensation is made for the 72 microphone and 12mm spacer combination The mean pressure and sound intensity spectra can then be measured at frequencies up to 10 kHz one octave higher than the normal theoretical limit DETECTORS Linear Integration 1s to days in 1s steps Overload Detector Monitors the two channels for overload AUTORANGE Manual and automatic range controls are provided SPACER SETTINGS Spacer Length 6 200 mm in 0 5mm steps AMBIENT CONDITIONS SETTINGS Measurements are automatically compensated for the current temperature and ambient pressure set by the user TRANSDUCER DATABASE The microphone pair is described in the transducer database with information on Serial No Preamplifier ID Nominal Sensitivity Polarization Voltage and Free field Type In addition to 2 Microphone Pair Type 4197 2 Microphone Pair Type 4181 and Microphone Pair Type 4178 consisting of two phase matched Microphones Type 4939 are supported CORRECTION FILTERS For microphone pair Types 4197 and 4181 the analyzer is able to correct the frequency response to compensate for Ellipsoidal Windscreen UA 0781 Minimum pressure
132. uble Rows or Columns Columns ANSI 12 12 only Segment Height 0 01 to 500m Use this parameter to specify the height of a single segment The area of the segment is used for calculating the Sound Power from the Segment Segment Width 0 01 to 500m Use this parameter to specify the width of a single segment The area of the segment is used for calculating the Sound Power from the Segment APPENDIX A Setup Parameters 115 A 6 Signal recording requires license for Signal Recording Option BZ 7226 Parameter Values Comment Recording Mode Off Set to Automatic to start the recording when the Automatic measurement is started and record throughout the measurement Recording Quality High 20 kHz This setup determines the quality of the recording by Medium 10 kHz adjusting the sampling rate Fair 6 6 kHz The amount of space required for the recording will Low 3 3 kHz depend on the selected quality please see details in the specifications chapter Resolution 16 bit Set Resolution to 24 bit to cover the full dynamic range 24 bit Set Resolution to 16 bit to cover up to 96 dB from the Input Range Setting High range or Low Range and down NOTE 24 bit at High 20 kHz recording quality is not available for hardware versions 1 3 A 7 Output Socket Signal Parameter Values Comment Source Off Choose Generator to enable the generator output that is Intensity AF specified in
133. uced by F the factor cos 0 if sound is incident at an angle to the p robe axis Sound propagating at an angle to the probe axis CHAPTER 6 Theory and Practice 3 Effective Spacer Distance Ar cos Phase change _ Arcos 360 Across Spacer x Sound propagating a along the probe axis Phase Change Across Spacer _ Ar 360 6 8 Reference Levels j 860793 1 The sound pressure intensity power and particle velocity levels Lp Ly L and L respec tively are all measured in dB Decibels are a ratio of the specified quantity measured against some reference For pressure the reference level is chosen so that it corresponds approximately to the threshold of hearing Other reference levels have been approximately related to this by using the free field relations between pressure and intensity and pressure and particle velocity Therefore in a free field the same dB reading will be obtained regardless whether one measures pressure intensity or particle velocity measured in the direction of propagation Sound Pressure n Lp 10log gt Po 6 Po 20uPa 20 10 Pa Sound Intensity I L saoer l 1pWim 1 10 W m 6 9 6 10 Sound Intensity Software BZ 7233 User Manual Sound Power W Ly Hogi Wy 1pW 1 10 w Particle Velocity 2 L 10log 5 Vo vo 50nm s 50 10 m s Actually because round numbers have been chosen for
134. ues from a selectable frequency band are displayed together with quality indicators e The surface can be superimposed on an image e The transparency of the colors can be adjusted TOTAL VALUES Single values displayed as numbers Sound Pressure Sound Intensity p index all Z or A weighted COMPASS For display of the direction of the incident sound energy near the probe Result Displays SPECTRUM Display of one or two spectra plus calculated Z and A weighted totals Quality indicators are shown below each frequency band Available Spectra per segment surface and total surface Sound pressure Z or A weighted sound intensity Z or A weighted p I index dynamic capability sound power Z or A weighted Y axis Range 5 10 20 40 60 80 100 120 140 or 160 dB Auto zoom or auto scale available Available spectra per segment Scan difference repeatability limit Available spectra for the total surface Field non uniformity field non uniformity limit extraneous noise convergence index convergence index limit Cursor Readout of selected band and quality indicator for each frequency band SPECTRUM TABLE One or two spectra can be displayed in tabular form SURFACE For display of all the segments organised in a rectangle e The segments are displayed in the correct height width ratio A grid can be superimposed on the surface The surface can be superimposed on an image Number The values from a selectabl
135. und Intensity Software BZ 7233 User Manual Fig 3 18 Surface setup 16 00 10 For example To set up a simple box a b c d Select Total Surface Type Box Set Surface Height and Surface Width for each surface select the surface using the Selected Surface parameter For Front set Surface Height 1 2 m and set Surface Width 1 5 m For Left set Surface Width 1 6 m Surface Height for Left is equal to Surface Width for Front All surface dimensions are set now Settings for Front is equal to settings for Back Left is equal to Right and Top Surface Width is equal to Front Surface Width and Top Surface Height is equal to Left Surface Width Fig 3 19 Left Result gt Select Total tab and select Number instead of List in the status panel to get an overview of the box Right Hypothetical box surrounding a noise surface 5 Close the Result display select the Spectrum tab and select Front in the status panel Fig 3 20 CHAPTER 3 Setting up the Analyzer z 6 Position the probe at the centre of the segment Place the probe on the measurement plane with the axis oriented normal to the surface Let the curved part of the probe point towards the plane such that the acoustical centre of the probe the middle of the spacer not the tip of the probe is bisected by the plane 7 Press 4 and measure for the full time period that was stipulated in Setup 8 Examine the spectrum a If the
136. ure measurements provide the data needed to determine if workers risk hearing damage If the workers are at risk noise reduction is needed To do this the amount of radiated noise and the source s must be determined Therefore the sound power of the individual machines must be measured and ranked by their sound power After locating the machine making the most noise we may want to reduce the noise by locating the individual components radiating noise Intensity measurements can accomplish all of this Measuring pressure will depend on the sound field Sound power can be related to sound pressure only under carefully controlled conditions where special assumptions are made about the sound field Specially constructed rooms such as anechoic or reverberant chambers fulfil these requirements Noise sources have to be placed in these rooms to calculate sound power Sound intensity however can be measured in any sound field No assumptions need to be made This property allows all the measurements to be done directly on site In addition measurements on individual machines or individual components can be made even when all the others are radiating noise because steady background noise does not contribute to the sound power determined when measuring intensity Because sound intensity gives a measure of direction as well as magnitude it is also very useful when locating sources of sound Therefore the radiation patterns of complex vibrating machinery
137. us SJ or Fahrenheit US UK set in Preferences gt Regional Settings gt Temperature Unit b Tap Ambient Pressure and enter the current barometric pressure 6 Screw the intensity coupler onto its base 7 Insert the dummy microphone into port 3 8 Insert one microphone into port 1 and one into port 2 9 Place the pistonphone on the intensity coupler The pistonphone intensity coupler and microphones should now be arranged as shown in Fig 3 12 NOTE This is a very tight fit Press firmly and ensure that the microphones are fully seated to avoid erroneous results Fig 3 12 Arrangement for sound pressure calibration 960114 2 a 3 3 3 Sound Intensity Software BZ 7233 User Manual NOTE Do not place the coupler in a warm area for example on top of measuring equipment as heat affects calibrations 10 Set up Type 2270 for sound pressure level calibration 11 Switch on the pistonphone 12 Tap Calibrate and wait for it to finish 13 Switch off the pistonphone 14 Remove the pistonphone from the top of the coupler Phase Calibration and Verification Phase calibration and pressure residual intensity index verification are part of the complete calibration process and should follow after sound pressure level calibration however they can also be performed individually If calibrating and verifying phase by itself perform steps 1 through 8 and then continue from step 15 15 Mount Sound Source
138. utton Fig 5 7 Scaling the Y axis on the Spectrum display o gt 10 kHz 16 6 d sa 10kHz 17 7 dB 4k 10k AZ 11 40 14 4 B Select Auto Zoom to adjust the range of the Y axis for best fit of the measured spectrum Select Zoom In Zoom Out to adjust the zoom Select Scale Up Scale Down to adjust the scale value on the Y axis or select Auto Scale to select the best scaling for viewing the spectra without adjusting the zoom Spectrum Table displays the spectrum in tabular form as in Fig 5 8 Tap the Table Format icon E top of the screen to select between three different formats Two Parameters for displaying values from both spectra One Parameter for displaying values from the main spectrum only together with the details on the smileys at the individual frequency bands One Parameter wrap for displaying values from the main spectrum only but with the columns wrapped on the display to allow as many values as possible on the screen a Fig 5 8 Spectrum table 5 2 1 5 2 2 Sound Intensity Software BZ 7233 User Manual Spectrum Table 3 To exit the Spectrum table tap EJ 4 Auto Zoom and Auto Scale automatically close the drop down menu otherwise select Close tap outside the drop down list or use the pushbutton to close the menu Hint a quick way of auto zooming is to tap anywhere in the spectrum and then press the Accept pushbutton twice NOTE
139. view of how many different quality indicators there are for a spectrum select the spectrum table tap the y axis and display One Parameter see Fig 5 8 Temporal Variability Temporal variability is selected by the SI Task selector in the upper right corner of the display The Temporal Variability indicator F1 is defined in ISO 9614 1 as an assessment of whether or not the sound field is stationary F1 is the normalized standard deviation of 10 successive short measurements To measure the temporal variability indicator measure at a typical measurement position on the measurement surface The measurement will last for 10 times the Short Averaging Time selectable below the spectrum When the measurement has been made the temporal variability indicator is calculated and displayed together with the limits defined by the standard Quality indicators are set at frequency bands that violate the limits If the temporal variability indicator is above the limit at frequencies of interest take actions to reduce the temporal variability of extraneous noise measure during periods of less variability or increase the averaging time at each segment The result is automatically saved as part of the current project The temporal variability indicator can be measured and calculated regardless of the chosen standard The Total Power A will get a smiley if temporal variability is too high however only if ISO 9614 1 has been selected as the standard
140. wing status information is available for each frequency band or segment Data excluded Dynamic capability too low Overload Underrange Repeatability failed Extraneous noise too high Averaging time too short Convergence index failed High levels outside Tot A frequency range Temporal variability too high Sound field is non uniform Quality Indicators based on status information are shown in the measurement displays Measurement Displays SPECTRUM Display of one or two spectra plus calculated Z or A weighted totals Quality indicators are shown below each frequency band Available Spectra Sound pressure Z or A weighted sound intensity Z or A weighted p l index dynamic capability scan difference repeata bility limit Y axis Range 5 10 20 40 60 80 100 120 140 or 160 dB Auto zoom or auto scale available Cursor Readout of selected band and quality indicator for each frequency band SPECTRUM TABLE One or two spectra can be displayed in tabular form Sound Intensity Software BZ 7233 User Manual SURFACE For display of all segments organised in a rectangle e The segments are displayed in the correct height width ratio A grid of segments can be superimposed on the surface Segments are coloured in accordance with the measurement status The current position is green when measurement is in progress and yellow when paused and not saved All segments with saved data are blue The val
141. xial LEMO Input Impedance 21 MQ Direct Input Max input voltage 14 14 Vpeak CCLD Input Max input voltage 7 07 Vpeak CCLD Current Voltage 4 mA 25 V TRIGGER SOCKET Connector Triaxial LEMO Max Input Voltage 20 Vpeak Input Impedance gt 47 KQ Precision 0 1V OUTPUT SOCKET Connector Triaxial LEMO Max Peak Output Level 4 46 V Output Impedance 50 Q HEADPHONE SOCKET Connector 3 5mm Minijack stereo socket Max Peak Output Level 1 4 V Output Impedance 32 Q in each channel MICROPHONE FOR COMMENTARY Microphone which utilises Automatic Gain Control AGC is incorporated in underside of instrument Used to create voice annotations for attaching to measurements CAMERA Camera with fixed focus and automatic exposure is incorporated in underside of instrument Used to create image annotations for attaching to measurements Image Size e Hardware versions 1 3 640 x 480 pixels e Hardware version 4 2048 x 1536 pixels Viewfinder Size 212 x 160 pixels Format jpg with exif information Storage INTERNAL FLASH RAM NON VOLATILE For user setups and measurement data e Hardware versions 1 3 20 MB e Hardware version 4 512 MB EXTERNAL SECURE DIGITAL MEMORY CARD SD and SDHC Card For store recall of measurement data EXTERNAL COMPACT FLASH MEMORY CARD Hardware Versions 1 3 Only CF Card For store recall of measurement data USB MEMORY STICK Hardware version 4 only For store recall of measur
142. y close to a source air acts as a mass spring system that stores energy The energy circulates without propagating a reactive field and the region in which it circulates is called the near field For determining sound power only sound intensity measurements can be made here And because it is possible to get close to the source the signal to noise ratio can be improved Particle Velocity When a particle of air is displaced from its mean position there is a temporary increase in pressure The pressure increase acts in two ways to restore the particle to its original position and to pass on the disturbance to the next particle The cycle of pressure increases compressions and decreases rarefactions propagates through the medium as a sound wave There are two important parameters in this process the pressure the local increases and decreases with respect to the ambient and the velocity of the particles of air which oscillate about a fixed position Sound intensity is the product of particle velocity and pressure Intensity Pressure x Particle Velocity In an active field pressure and particle velocity vary simultaneously A peak in the pressure signal occurs at the same time as a peak in the particle velocity signal They are therefore said to be in phase and the product of the two signals gives a net intensity In a reactive field the pressure and particle velocity are 90 out of phase One is shifted a quarter of a wavelength with re
143. y to Survey Detailed views of p I index and Dynamic Capability available for each segment surface and total surface Extraneous Noise Evaluate Do e No limit stated for Do e Definition Dye Oo i Extraneous noise e Extraneous noise checked against 3 dB for each frequency band in the total surface If non compliant Yellow smiley for Extraneous Noise too high for each frequency band Detailed view of Extraneous Noise available for the total surface Calculation of Sound Power e Calculate the sound power from each segment by multiplying the sound intensity by the area of the segment e Calculate the total sound power by adding the sound power from all the segments Calculation of Sound Power e Sound power is automatically calculated for the displayed segment surface or total surface Calculation of A total e Calculate A total from all the frequency bands A total is calculated on all segments surfaces and total surface using all frequency bands Increase accuracy In order to guarantee upper limits for uncertainties of the sound power levels determined certain actions have to be taken if D24 and Ds are not fulfilled See Hints for Improving Accuracy CHAPTER 6 Theory and Practice 99 6 16 5 None No Standard Used Using no standard is useful in mapping sound intensity for the identification and quantification of noise sources Measurements will typically be

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