Home

Nor-118 User Manual Extension V2

1. Select AC out or Noise Press SETUP and 1 for selecting instrument set up Follow the sequence shown on Fig 10 2 This enables three choices for the analogue output 64 Extensions and Options 11 12 13 14 15 16 17 18 Instr menu Misc menu Storing Prnt par IO Print Xfer par Clock Unit Id Pol volt SModeRUN 2nd netw Ana Sig Correct Version Misc par Se sek KA A Ke Fig 10 2 AC out Noise gen BIS Set the analogue output signal to noise output Note that the contents in each menu will depend on the options installed e Off no signal e AC out replica of the microphone signal e Noise generator Noise ctrl Move the field cursor to Noise gen as shown on Fig 10 2 and press Gen Sync ENTER repeatedly until you are back in the required display OFF ON The parameters for the noise output are set in a separate menu Type PINK Rev setup Press SETUP and N Ex time 3 BIS be entered as a numeric value Press operation Fig 10 3 Setup menu display to move the field cursor Use the key on the right side of the display to change the content The gain may Selecting noise type and level for selecting noise set up menu A dialogue box as Ex typ e NOS shown in Fig 10 3 will be shown Use the arrow buttons below the Increase and Decrease ENTER t
2. 2 3 The result may be further corrected to obtain the standardised and normalized sound pressure level Norsonic Nor118 User Guide 6 Speech Intelligibility by STIPA Option 13 6 1 6 1 1 6 1 2 Introduction What is STIPA Speech transmission index STI The speech transmission index STI has shown to be a valuable tool for objective rating the speech intelligibility From its first presentation in Acustica in 1971 the method has been refined and developed for various applications Recently the International Electrotechnical Commission TEC has launched the third revision of the International Standard specifying the method for calculating the index as IEC 60268 16 Essential for this development was the work carried out at TNO Human Factors in the Netherlands and in particular the pioneers Tammo Houtgast and Herman Steeneken The STI methods can be used to compare speech transmission quality at various positions and under various conditions within the same listening space in particular it is useful for assessing the effect of changes in acoustic properties This includes effects from the presence of an audience or of changes in a sound system The methods are also able to predict the absolute rating of the speech transmission quality with respect to intelligibility when comparing different listening spaces under similar conditions or assessing a speech communication channe
3. 2005 All rights reserved Norsonic Nor118 User Guide Contents A AAA EE 5 2 Engineering Hr LCE 7 2 1 PU SUI RE 7 2 2 Selecting Engineering Uns eC 7 2 3 How valies are indicated ertt eh ente tee eet teen iere eU epe ca ii 7 2 4 Relation Detween dB and EU eie ii dido 8 2 5 6 1 17 711 C X 9 d Mode related Ege 11 3 1 nr m 11 3 2 Global parameters ciaicicioniinci 11 3 3 Mode dependent parameters ii 12 3 4 Standard set p E 12 Remote BA Option tee ee Eed 15 Building Acoustics Survey Option 12 uuunusssusnnnnnnnnnnnnnnnnnnnnnnnnannnnnnnnnnnnnnnnnnnnnannnnnnnnnnnnnnnnannnnnan 17 5 1 LE 17 5 2 ERR 18 5 2 1 General 32 2 JTerms and definitions s ct eve doeet cedi a aeo ea ODE e e ERE E a ee CREER ERN e EG ids 18 2 2 3 Noiseexceltdtionz eet enee eerte uie atem edet eria te ed 19 32 4 Measurement NEE 20 5 2 5 Measurement of reverberation time esee eee enne teinte teen rre en tenete erre nre 20 35 2 6 Calculating the result ed esos tete e et ese e e EON RS UR ER ERE I E FINE Re ee ee adden 20 3 27 Store and recall sete rt Tp e OT e D eee do e 22 5 3 Impact sound insulation m iia 22 5 3 1 Terms and COJONES A I O EE OEA E E A Ter cte PALE 22 5 3 2 Impact excitation KE GEET level EE 23 5 3 4
4. If you don t know the self noise of your particular instrument within 2 dB don t use the optional correction for self noise Otherwise the correction may make more harm than good The self noise should be measured with the actual microphone after proper calibration of the instrument Note that a dummy microphone often used for checking the self noise of an instrument cannot be used Use of a dummy microphone will only indicate the electrical noise of the system and not the noise related to the acoustic impedance of the microphone If you don t have access to a required quiet place the instrument may be placed inside a closed vessel placed on a place with low vibration We recommend using some acoustic damping material in the vessel If you have the Trigger option Option 16 we recommend to use the clock trigger for starting a measurement after the vessel is closed 71 Norsonic Nor118 User Guide 12 Extensions and Corrections to Nor118 User Guide November 2002 800Hz C Fig 12 1Reverberation decay curve 12 1 12 2 Analogue high pass filter The cut off frequency of the third order HP filter has been changed from 4 Hz to 3 Hz 3 dB Ref p 83 Measurement of reverberation time With software version 2 0 it will be possible to display the decay after the measurement of reverberation time see Figure 12 1 To display the curve press 24 P A key after the measurement The decay will not be stored
5. 500 Hz 0 06 630 Hz 0 05 800 Hz 0 04 1 kHz 0 03 1 25 kHz 0 02 1 6 kHz 0 02 2 kHz 0 02 2 5 kHz 0 01 3 15 kHz 0 01 4 kHz 0 01 5 kHz 0 01 6 3 kHz 0 01 8 kHz 0 01 10 kHz 0 01 12 3 Calibration A change has been made in the program to make it easier to view the calibration value and return to the normal mode of operation As before a press on the button display the calibration menu However a 12 4 Norsonic Nor118 73 User Guide second operation brings the instrument back to the normal mode of operation As before you may also return by pressing ENTER If you need to write in a sensitivity value starting with zero E g 0 5 just skip the zero and start with the decimal point Store and recall of set up information Many parameters have to be set up to control the performance of the instrument Adding program options increases the number of parameters that have to be set Once you have set up the instrument for a certain task you may want to store this information in order that it may be recalled when a similar measurement has to be made at a later date In order to store the set up parameters and the selected mode of operation press STORE before a measurement is started All setting will be collected in a directory called SETUP and numbered consecutively The number is suffixed with a letter indicating the mode of operation L indicates normal mode of operation level indicates
6. Measurement of reverberation mie 24 2 3 9 e 24 2 Extensions and Options 11 12 13 14 15 16 17 18 3 3 0 Store and recalls dis li ette cie a a T nina sb 26 5 4 ECCOLCIRSULACOA MEE 26 5 4 1 General de Ta CO REP EDITO UNIO NEE aT eC ren er PNE 26 3 4 2 Terms and definitions 5 ete RE RESP EAM ERREUR SERE Ree RR UE De oe ang Seres dE 26 5 4 3 Noise excitation 5 44 Measurement of sound level oes e e e od ee eR ne P dec na ei Pea d 28 5 4 5 Measurement of reverberation time esses eene ener eterne entente neret nenne 28 5 4 6 Calculating the result KEE 5 5 Service equipment sound pressure levels uuscrsesssessosssnssnnsnssnonsnnnsnnsnnsnonsnnnsnnsnssnnnsnnsnnnsnnssssnonsnnssnsssssnonsnnssnnssssnansnnssnne 30 Speech Intelligibility by STIPA Option 13 eere 33 6 1 Introduction What is STIPA A o iii 33 Doll Speechitransmission index STIL as b eie e iR S Cer ede pet ended EA 33 NEE EE 33 6 1 3 RASTI and STIPA GTA C Howus STIPA measured s A A A EE co No bo TO PT a Pe EO Ado OG ERROR 36 MEME SEE 37 6 2 Units included iri delivery t crios 6 2 1 Software option for Nor I8 RR 6 2 2 EDO excitation sien fc ot nie tU tm OR et e rives irm iE wa E dr Ere 6 2 3 Printed Instruction manual sss 6 2 4 CD with Excel sheet and Instruction manual essent eren enitn eene eene 6 2 5 Not included CD player and loudsp
7. a noise signal with a high crest factor a spectral distribution similar to the long term speech spectrum and that the main modulation frequency is selected one by one The measurement of the full STI therefore has to be performed as a sequence of measurements If each of the 98 combinations is measured for 10 seconds the total measurement time will be about a quarter of an hour The need for such a long measurement time in order to obtain the STI value in one position of a room limits the applicability of the full STI method The STI method may be modified in different ways to reduce the time needed for the measurement If the system to be measured is regarded as linear then a number of solutions exist The excitation signal may be modulated with all modulation frequencies simultaneously and the components may be separated after reception by the use of filters or Fourier analysis A more common method is to calculate the complex modulation transfer function from the impulse response of the room If the impulse response can be regarded as a well behaved room response with an exponential decaying envelope characterised by the reverberation time the modulation transfer function at frequency F may be calculated directly from the value of the reverberation time T and the effective signal to noise ratio S N in dB A simplified formula not taking the Norsonic Nor118 35 User Guide effects of masking and the threshold of hearing into consid
8. cursor is in the field for reverberation time marked T If you want to estimate the absorption as described in ISO 10052 move the cursor to the field marked E and press ENTER By specifying the type of room and the covering for walls ceiling and floor you are entering data corresponding to Table 3 in ISO 10052 When the required information is specified the cursor will automatically be placed in the field for calculation of the final result If you are satisfied with the values press or if you want to make any corrections move the field cursor to the required field and enter the corrected values 30 Extensions and Options 11 12 13 14 15 16 17 18 5 4 7 5 5 When you move the field cursor to the field Calc result and press ENTER the following functions are calculated for each of the octaves bands 125 Hz to 2000 Hz e The normalised level difference D e The standardised level difference D r e The apparent sound reduction index R R45 e The source room level L e The receiver room level L e The reverberation index k e The reverberation time T For the values D Dnr and RI a frequency weighted value according to ISO 717 1 is also calculated together the correction terms C 1252000 marked as C and C 125 2000 marked as Cy Pressing the key repeatedly will display the different functions The weighted values are all rounded to the nearest whole dB If you want to g
9. diameter of maximum 100 mm and refers to ITU T Recommendation P 51 describing an artificial mouth A sound source according to this specification is available from different manufacturers with a typical example being the GRAS 44AA When speech is relayed through a sound system a simulator is not normally required unless a close talking or noise cancelling microphone is involved Performing a measurement General Most applications require that the excitation is performed using a small loudspeaker acting as a human talker However same applications such as testing public address or voice alarm systems are more conveniently tested with the electrical signal from the CD player fed directly into the system to be tested 42 Extensions and Options 11 12 13 14 15 16 17 18 16 125 1k _8k AZ 0 05 Fig 6 3 Display during measurement of STIPA STI 0 62 Good CIS 0 79 LA 533 NCorr Fig 6 4 Main result display 6 4 2 6 4 3 6 4 4 In a similar way some applications related to test of transmission channels require an electrical signal as the input to the sound level meter for analysis For this application the microphone preamplifier may be substituted with a cable to the input socket of the sound level meter NOTE For this description a measurement set up with acoustic excitation and detection using the normal measurement microphone is assumed Set up Set the sound source artificial mouth or
10. e UnA 51 7 2 Howto select the EFI iia 51 7 3 Making a a a 51 7 4 OI IT Rt 53 7 5 EHEN 53 7 6 KR diia 53 7 7 Specification as 54 8 Reference Spectrum Option 15 uuussressnnnnnnnannnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnannnnnnnnnnnnnnnnannnnnannnnnnnnnn 55 8 1 0 2 77 E 55 8 2 Activating the Reference Spectrum features uzneseesnrsusnunsesnunnesnsnnnsusnnnsernunnnnnssnnsusnansnsnussesnssnsnassennsssssnssansssnansesnnsnnsnnne 55 8 3 Selecting the Reference EE 56 8 3 1 Using a previously measured spectrum ran 56 6 3 2 Entering a new reference spectrum manual 56 6 3 3 X Editing a selected Reference Spectrum sese anna ran 57 8 4 A pre weighted Reference Spectrum ccscscssssssccrsscssssecseacssesssscsescscesscsescucesesecseacscessseeacaceasseeseacaceseaceceseeeeecaceaeseseeaenees 57 8 5 WG WOW 57 ade SDieitaboutpub LINES edel er estet e iR TN ERR OR Te EE 58 9 Trigger Option 16 rere nre reete De aaa Er a aan ge deme d teer oem er Rire 59 9 1 GOCE E ese 59 9 2 Selling the trigger Condition RR 60 9 2 1 Manual trigger 92 23 MELO CIO etiem br eet hee ir e n er e ere et ries pe nee ege 92 3 External trigger ee ee i ER Pe e PE VETE ESI E HD Nadando eR e Ed e den 61 924 SL evekabovestrigger rn conca oth 61 10 Noise Generator Option 17 uusuunssannnnnnnnnunnnnnnnnnnnnnnnnnnnnnnnnnnnnannnnnnnnnannnnnnnnnn
11. spectra activated 49 1 8 5 1 End The Go NoGo comparisons functions only after the measurement has been ended or stopped The status of the Go NoGo comparison is displayed as a Go or a NoGo symbol within the L f display As the Reference Spectra only contain dB values the currently selected spectra function Leq Lmax Lmin etc selected by the FUNC key will be the basis for the comparison of the actual measurement spectrum with the currently stored and selected Reference Spectra All frequency band values of the actual measured spectrum must fulfil the actual requirements of the saved Reference Spectra in order to get a Go status In cases where all frequency bands must be above or below the Reference Spectrum in order to get the desired Go NoGo status a selection of the respectively Lower or Upper Reference Spectrum as limits will perform the required operation Alternatively selecting both the upper and lower Reference Spectra requires that the measured spectrum must be between these two Reference Spectra for all frequency bands that contain values Digital output lines The digital output line on pin 2 of the I O socket follows the Go NoGo status as described above Hence this output pin goes high when any frequency band within the measured spectra is above the upper reference spectra or below the lower Reference Spectra If only one of the Reference Spectra is ac
12. 0 2 the reading will have a high degree of reliability If the background noise can be switched off it is possible to measure the response to the STIPA excitation and noise level separately The STI value may be corrected for the background noise later in the instrument or by applying the Excel sheet STIPA calc delivered with the instrument option This will eliminate the interference between a spiky noise signal and the STIPA method Precision of the STIPA method Because the test signal is band limited random or pseudo random noise repetition of measurement does not normally produce identical results even under conditions of steady interference The results centre on a mean with a certain standard deviation Typically the value of the standard deviation is about 0 02 with stationary noise interference With fluctuating noise for example a babble of voices higher standard deviations may be found possibly with a systematic error This can be checked by carrying out a measurement in the absence of the excitation signal This should result in a residual STI value less than 0 20 An estimate of the standard deviation should be made by repeating measurements for at least a restricted set of conditions Analysis and interpretation of the results It is Important to examine the modulation matrix to determine the reliability of the results As a rule the modulation index in each octave band should decrease with increasing modulat
13. 1 3 Linearity error without and with correction Linearity error without correction Ni EN NUMEN NNNM NEN ILI AAA 0 16 18 20 ded mur Lom Se Ee dB Linearity error dB Linearity error with correction Correction 1 dB to low TARTE n Ideal correction ERI E E Linearity error dB Correction 1 dB to high 3 0 2 4 6 8 10 12 14 16 18 20 Sound level above self noise level dB Noise correction LnA 15 0 Lnc 19 0 LnZ 25 0 EB S 4 Fig 11 4 Parameters for noise correction Norsonic Nor118 69 User Guide Set up for correction Press SETUP and 1 for Instrument set up See Figure 11 1 Press 6 for the correction menu Move the field cursor to S noise self noise and toggle the value to ON by using the Increase and Decrease keys on the right side of the display See Figure 11 2 Press 1 for correction parameters The display as shown on Figure 11 4 will appear Enter the values in dB for the self noise for the different weightings A C and Z Use the arrow keys to move the field cursor between the fields Press ENTER after entering a numeric value and for leaving the menu Measuring the self noise The self noise of a sound level meter is the indication on the meter when the instrument is placed in a quiet place where the actual sound pressure level is considerably 20 dB less than the self noise
14. 10 mega G 10 giga T 10 terra ec 9 An underscore is used if no other postfix characters apply The following examples may illustrate the principle 189m gt 189x10 gt 0 189 78 3u gt 78 3x10 lt gt 0 0000783 Relation between dB and EU The logarithmic dB scale is a scale relative to a common reference value In the Nor118 instrument the reference value is always 2x10 corresponding to the common reference pressure for sound pressure levels 20 uPa A linear quantity X will therefore correspond to a level L x L 20 wel X where X 22x10 This implies that 1 EU corresponds to 93 979 dB or as usually stated 94 dB Set the sensitivity level L to OdB The indication in engineering units will then correspond to the voltage of the signal presented at the input terminal microphone socket 2 5 Norsonic Nor118 User Guide Calibration The sensitivity is always expressed as a logarithmic sensitive in dB relative to 1 volt EU Even if engineering units are selected the sensitivity still has to be specified in this way However if a calibration signal is presented to the input the indication will be in engineering units or decibel dependent upon the selected setup Use the INC or DEC keys as usual for adjusting the sensitivity in 0 1 dB step If you want to calculate the sensitivity some examples may clarify the procedure Example 1 A microphone with preamplifier h
15. Im118 2Ed2ROEn March 2005 Extension to Instruction Manual Sound Level Meter Nor116 Software version 0 SS Options Remote BA Building Acoustics Survey Speech Intelligibility STIPA FFT Reference Spectrum Trigger Noise Generator Self noise Compensation NN Norsonic Extension to Instruction Manual Sound Level Meter Norl18 Options y Remote BA Building Acoustics Survey Speech Intelligibility STIPA FFT Reference Spectrum Trigger Noise Generator Self noise Compensation Nor118 User Guide for Option 11 12 13 14 15 16 17 and 18 Im118_2Ed2R0En March 2005 edition Norsonic is a registered trademark of Norsonic AS Every effort has been made to supply complete and accurate information However Norsonic AS assumes no responsibility for the use of nor for the consequential damage of the use of this information and or the instrumentation described herein Furthermore Norsonic AS assumes no responsibility for any infringement of the intellectual property rights of third parties wherever applicable which could result from such use Norsonic AS reserves the right to amend any of the information given in this manual in order to take account of new developments If you wish to communicate with us please feel welcome Our address is Norsonic AS P O Box 24 N 3421 Lierskogen Norway e mail info norsonic com Find us on the web www norsonic com Copyright Norsonic AS 2004
16. Nor 18 Norsonic Nor118 67 User Guide 11 Self noise Compensation Option 18 Instr menu Storing IO Print Clock Pol volt 2nd netw Correct Version Eo SOU Wh Misc par Fig 11 1 Instrument menu Correction windscr OFF S noise lI Corr par BS S Fig 11 2 Correction menu General When measuring very low levels the indicated level may be influenced by the self noise of the instrument If you measure an A weighted level of 25 dB which is about 10 dB above the typical self noise of 15 dB the contribution from the noise will make the reading to be 25 4 dB or 0 4 dB too high Option 18 allows the A weighted and C weighted Z weighted levels to be corrected before they are displayed The correction is done by subtraction of the energy related to the self noise Figure 11 3 shows the linearity error as a function of the difference between the true sound level and the self noise level The upper part shows the error without compensation and the lower shows the error with ideal compensation and for a compensation where the estimated self noise is 1 dB and 1 dB from the real self noise level The correction is based on the following equation Lc 10 log 0 19 5 where Lm is the measured level signal plus self noise Lnoise is the self noise level and Lc 1s the corrected level shown on the display 68 Extensions and Options 11 12 13 14 15 16 17 18 Fig 1
17. and can therefore not be displayed for recalled measurements The frequency may be selected by cursors keys A higher and Y lower The compression factor C for the time axis may be are adjusted in a power of 2 sequence by the keys gt I Compress and ER zoom respectively The cursors is moved along the frequency axis by the cursor keys 4 and gt If the cursor is in the left or right extreme position the spectrum will scroll about 1 4 of the displayed frequency range In the Main User Guide November 2002 is stated that no reverberation time will be indicated if the instrument is overloaded during the measurement This is not the case The values are indicated as calculated but an overload mark is placed in the upper part of the table The lower limit for the for reverberation time has been changed in software version 2 0 If the measured result are below the following values the result will be marked as unreliable since the result will be affected by the virtual reverberation time of the filters 72 Extensions and Options 11 12 13 14 15 16 17 18 Table 12 1 Lower limit for reverberation time Frequency Lower limit seconds 50 Hz 0 60 63 Hz 0 48 80 Hz 0 38 100 Hz 0 30 125 Hz 0 24 160 Hz 0 19 200 Hz 0 15 250 Hz 0 12 315 Hz 0 10 400 Hz 0 08
18. as a sensitivity of 50 mV Pa or 0 05 V Pa The SI unit pascal Pa is now used as EU The logarithmic sensitivity will be H 0 05 L 20 wl 26 0 dB EU If tels is selected the sound pressure will be indicated in dB relative to 20 uPa If is selected the signal will be indicated in pascal Normal levels will correspond to the root mean square value RMS but the peak value will correspond to the absolute value of the pressure peak Example 2 The combination of an accelerometer and an amplifier has a sensitivity of 20 mV ms The unit for acceleration ms is now the engineering unit The logarithmic sensitivity will be 0 02 Tom mell 34 0 dB EU Setting the instrument to this sensitivity and selecting will make the instrument indication to be vibration expressed as m s Norsonic Nor118 11 User Guide 3 Mode related Set up 3 1 3 2 General A new feature introduced with the software version 2 0 is that the set up parameters are stored separately for each mode of operation This has been a growing demand since the number of modes of operation for the instrument is steadily increasing Due to this feature you don t have to readjust the filter bandwidth to 1 3 octave due to a previous measurement of STIPA which requires a full octave bandwidth Storing of a particular set up may be done as before Press STORE when the instrument is in ready mode and before a measurement is performed I
19. at should be visible Editing a selected Reference Spectrum Use cursor keys to move the field indicator in row with the frequency band to be edited Use the Incr and Decr keys to adjust the value in 0 1 dB steps or use the numerical keys to enter the desired new value Alternatively use the DEL key to clear the value If the values from one or more bands are deleted the Reference Spectrum indicators for these bands are NOT presented in the graphical display A pre weighted Reference Spectrum The Reference Spectra saved in the instrument are always stored with a linear or flat response However if the A pre weighting display feature is used during the comparison both the displayed Reference Spectrum and the measured frequency spectrum will be pre weighted Go NoGo Quality Control feature The Reference Spectrum feature may be used to give a Go or a NoGo output signal in quality control applications This additional feature is found in the lower part of the Freq Mode menu as the QC setting There are three selections for the QC feature Off No Go NoGo comparisons are made On The Go NoGo comparisons functions continuously before under and after the measurement 58 Extensions and Options 11 12 13 14 15 16 17 18 8k AC 0 16 125 1k 0 42 4 Leq 1 25kHz NoGo Fig 8 5 1 3 octave analysis with upper and lower refe rence
20. c address systems It also performs well for room acoustics and can therefore in nearly all cases replace the RASTI method and deliver results more closely to the values obtained by the full STI method The measurement time for a STIPA measurement is similar to the RASTI method 10 15 sec The STIPA method uses a higher degree of modulation for each test frequency It will thus be more robust for interference from non stationary background noise See figure 6 1 for a comparison between the methods 36 Extensions and Options 11 12 13 14 15 16 17 18 Carrier frequency Hz Carrier frequency Carrier frequency Hz d H H gt gt o o c o o 2 2 c c o o pad BS u c c 2 2 Ss Ss 2 o o o o Modulation frequency Hz 142511 I E STIPA Fig 6 1 For a STI measurement all carrier frequency bands are modulated with all modulation frequencies in total 98 modulation indices For RASTI two carrier frequencies are used giving 9 modulation indices For STIPA 12 modulation indices are measured from the complete range of carrier frequencies 6 1 4 How is STIPA measured The instrument option comes complete with a CD containing the excitation signal The excitation is played continuously through a loudspeaker and this acts as a talker The battery operated Nor118 sound level meter is placed in the position in the room where you want the speech intelligibility to be
21. corrected values When you move the field cursor to the field Calc result and press ENTER the following functions are calculated for each of the octaves bands 125 Hz to 2000 Hz e The normalised impact sound pressure level L e The standardised impact sound pressure level L r e The receiver room level L e The reverberation index k e The reverberation time T For the values L and L 7 a frequency weighted value according to ISO 717 2 is also calculated Pressing the FUNC key repeatedly will display the different functions The weighted values are all rounded to the closest whole dB If you want to go back to the menu for calculation press ENTER 25 26 Extensions and Options 11 12 13 14 15 16 17 18 5 3 6 5 4 5 4 1 5 4 2 Press the MODE button if you want to return to normal mode of operation Note that you have to be in the menu for entering values before you are able to select another mode Store and recall You may store the result by pressing STORE The file is automatically designated with the next free file number succeeded with the letter B indicating building acoustics Facade insulation General See ISO10052 for further details regarding requirements for the noise generating equipment and the selection of microphone positions Use of traffic noise for facade measurement is not covered i
22. ctively NA EEE The cursors is moved along the frequency axis by the cursor keys N o and gt If the cursor is in the left or right extreme position the spectrum M 156 will scroll about 1 3 of the displayed frequency range X BAR The cursor keys IE and moves the cursor to the extreme left hand or right hand position respectively A further operation of these Fig 7 2 Setting the measurement duration Y Zoom Number of periods in the F 050209 00055 110 F 050209 0005S 110 average Cursor frequency Hz Compression factor 366 21 581 54 C I N de 30 X 437 99 Fig 7 3 Move the cursor to obtain the digital vale for the spectrum at one particular frequency Use thefield cursors amp and Y to change the compression factor 7 4 7 5 7 6 Norsonic Nor118 53 User Guide keys will scroll the display along the frequency axis If the display is compressed more spectral lines are displayed as one line The cursor value will show the maximum value for all the lines represented by the cursor position In order to read the values for each spectral line you have to zoom until the compression factor is one C 1 The displayed level range may be scrolled by using the INC and DEC buttons as in normal mode of operation Calibration The instrument has to be calibrated in the normal mode of operation The readout may be in decibel or engineering units as described in section 2 Cor
23. dly will display the different functions The weighted values are all rounded to the nearest dB See Figure 5 5 If you want to go back to the calculation menu just press ENTER Press the MODE button if you want to return to normal mode of operation Note that you have to be in the menu for entering values before you are able to select another mode Store and recall You may store the result by pressing STORE The file is automatically designated with the next free file number suffixed with the letter B indicating building acoustics Impact sound insulation Terms and definitions The following terms are used in the display L average sound pressure level in the receiving room dB T reverberation time s To reference reverberation time equal to 0 5 s k reverberation index dB L r standardised impact sound pressure level dB L normalised impact sound pressure level dB Fig 5 6 Tapping Machine Nor211A 5 3 2 5 3 3 Norsonic Nor118 23 User Guide V volume of the receiving room m Ay reference absorption area equal to 10 m The relations between the quantities are given by the following equations Zu T Lr L k nT L L k 10 1g Ao 0162 V The values are calculated for each octave band For Lpr and Ln a single number value is also calculated The value corresponds to the value for the reference curve after shifted it in accordance wit
24. e band spectrum Fig 6 6 Two modulation indices are measured for each octave band 3 15 Hz Modulation index for 500 Hz octave band modulated with Norsonic Nor118 43 User Guide in the upper left corner of the display indicates the STI mode of operation The instrument screen will show the level versus frequency display Time constant will be F The cursor will be positioned for indication of the A weighted level Making a measurement Start a measurement by pressing the START button The measurement lasts for 13 seconds During the measurement the level versus frequency display will be shown together with an indicator of an ongoing running measurement see Figure 6 3 After the measurement is ended the main STI display will be shown after a short calculation period see Figure 6 4 For the first measurement after the STI mode is selected the Noise correction will be selected off and the cursor will be placed above the Off field The measured result will be indicated as a STI value together with an assessment of the intelligibility The STI value and the assessment are according to the STIPA procedure in IEC 60268 16 2003 05 for male voice The corresponding CIS value Common Intelligibility Scale according to IEC 60849 1998 02 is also indicated The mean A weighted speech level is indicated in dB relative to 20uPa If the measured value is detected as unreliable a question mark is p
25. eaker sees eene eren entente 6 3 Measurement Verview ELE 6 3 1 General instrument description 6 3 2 Selecting a loudspeaker for the excitation sese eene 41 6 4 Performing MEOSUTCMON 1 E 41 6 4 1 General CADA Sd ihe enia ide 643 Setihespeech levels sas ed b e Te e te id b ettet 6 4 4 Select the STI mode 64 Making measurement iss eda a ER FERREA EE KE AERE Pa lassen 43 6 4 6 Storeand recall he result stet eno Ee TR WR TOI RR EV 44 6 4 7 Correcting for background and occupancy Moise 44 6 5 Real background B m M 46 6 6 Precision of the STIPA method eene ettet rettet retta ta eroe Eee nennen ae Yo ER AEN Age Nee 47 6 7 Analysis and interpretation of the results eee eee ee esee esee en sete eite nttnt tnnt tn sine rr rre cora c coco ncnn coc ene en setae 47 Norsonic Nor118 User Guide 6 8 Limitations of the STIPA method cccccssccesssssesssssssessescencesscscsscsescesscscsscesenceccscescssescesesecsseeseesesessceseeseesesesnssseeseeseaeens 48 6 9 Using Excel for further calculations sersersessesnesnssusnansernunnennsnnnsnsnansusnussernssnnsnssnnsusnssnssnnsnsnonsennussssnsssssnsnassesnassesnssnnsen 48 6 10 DTH CO WWW A A A 50 6 11 Specifications A a 50 7 FFT measurement mode Option 14 unsuusnssnnsnnnnnnnnnnunnannnnnnnnnnnnnnnannunnnnnnnannnnnannnnnnnnnnnnnnnannnnnnn 51 71 AAA
26. ent You may use one of these set ups as a starting point for making your own version The standard set ups are placed in a folder marked STNDRD see figure 3 1 A description of the different set ups is found in the table on the next page If a set up for a particular mode is loaded the instrument is automatically set to the corresponding mode of operation independent of the previous mode Norsonic Nor118 User Guide Standard set up File Mode Measurm Time Trig Storing 2 Output Filter L t parameters Ref time resolution netw spect IL Normal 1h Inf Man Auto C AC out Off 0 2L Normal Ih ls Man Auto C AC out Off ALeq AFmax Cpeak 0 3L Normal 1h Inf Man Auto C AC out I l oct 0 4L Normal 1h Inf Man Auto C AC out 1 3 oct 0 5L Normal Ih ls Man Auto C AC out I l oct ALeq AFmax Cpeak 1 l octLeq O 6L Normal Ih ls Man Auto C AC out 1 3 oct ALeq AFmax Cpeak 1 3 octLeq O TR Rev Level Auto C Noise gen l l oct 0 8R Rev Level Auto C Noise gen 1 3 oct 0 9R Rev Level Auto C AC out 1 1 oct 0 IOR Rev Level Auto C AC out 1 3 oct 0 11P Power Asin C z normal mode 12B Survay BA 30s Inf Auto C Noise gen l l oct Off 13 STIPA 13s Man Auto C AC out I l oct Off 14f FFT NA 100 685 ms Man Auto AC out FFT Off Note For the measurement of rev
27. eration indicated the following relationship 1 1 m F TA 141055 M110 1 27F 4 0 As seen from this formula a limited signal to noise ratio reduces the modulation transfer function for all frequencies A long reverberation time reduces the modulation most for the highest modulation frequencies The STI value is a weighted average of the different modulation indexes The last revision of the method IEC standard also considers masking effects and the absolute threshold of hearing RASTI and STIPA In order to simplify the direct measurement the RASTI method Room Acoustic Speech Transmission Index was developed at TNO in 1979 Different instruments were developed for the measurement according to this standard A typical measurement time was 10 to 15 seconds The RASTI method only considers two octave bands 500 Hz and 2 kHz Due to the simplicity in use the RASTL instruments were used also for applications beyond the main design goal room acoustics The RASTI value is often used for assessing the quality of public address systems but comparisons with subjective measurements have shown that the deterioration of speech intelligibility is not handled correctly 1f the PA system is strongly non linear or suffers from limited bandwidth In order to improve the accuracy in the intelligibility assessment the STIPA method was developed It handles effects due to reverberation in the room and distortions commonly found in publi
28. erberation time 7R and 8R uses excitation from the internal noise generator option 9R and 10R specify impulse excitation from an external source as an impulse from a shot 13 Norsonic Nor118 15 User Guide 4 Remote BA Option 11 Fig 4 1 Nor1028 screens The Remote BA Building Acoustics option is required for operating the Nor118 as a building acoustic measurement device in combination with the NorBuild CtriBuild software package Nor1028 Option 11 requires all the options 1 3 6 7 9 and 17 to be installed in the Nor118 unit Option 11 in combination with the other required options includes all required remote commands for making building acoustic level or reverberation time measurements with the external CtrlBuild package Option 11 also extends the internal noise generator option 17 to include band pass filtered noise in addition to white and pink noise Further description of this option is given in the instructions for the CtrlBuild package Comparison A Leq dB B Leq dB Display Fullscale 120 dB Display Range 120 dB d Frequency 50 0 Hz Difference dB Display Fullscale 80 dB d Display Range 50dB 7 Difference Close Norsonic Nor118 17 User Guide 5 Building Acoustics Survey Option 12 DE Normal Rev Power SurveyBA STIPA FFT Fig 5 1 Mode menu 5 1 General The Building Acoustic Survey mode allows measurement of buildin
29. erformed the results may be stored in the non volatile memory of the instrument this is done by pressing the button Alternatively the instrument may be set up to store automatically after each measurement see the general instructional manual for Nor118 for information about the file structure A stored result may later be recalled See Figure 6 7 Correcting for background and occupancy noise The STIPA method considers the effect of the actual background noise when the intelligibility is assessed However in some cases we want to find out what the intelligibility would have been if we had a certain background noise A typical application will be to assess the intelligibility in an auditorium with audience when the auditorium was measured without For such applications the optional noise correction may be used Measure the STI value as described above Place the cursor above the field Off in Noise correction Off and press INC or DEC button to toggle the value to On The results will be recalculated to account for the specified background noise See Figure 6 8 Norsonic Nor118 45 User Guide STI 0 62 Noise edit Good 0ct Leg CIS 0 79 125Hz LA 53 3 250Hz 500H ON ENTER SCH d STI 0 38 gt oke Poor 4 0kHz CIS 0 58 8 OkHz Fig 6 9 Edition of the background noise level The result is corrected for a stored background noise spectrum If you want to edit the value
30. f you have a result in the display press EXIT in order to reach the ready mode The mode related set up covers most measurement parameters as selection of network measurement time time resolution frequency resolution etc However some parameters are global and adjustment in one mode will define these parameters also when the instrument is operated in a different mode Global parameters The following parameters are global and adjustment in one mode of operation for the instrument will be valid also in other modes of operation Instrument sensitivity calibration Polarisation voltage Calendar clock settings Serial interface on off and baud rate Second weighting network C or Z weighting Level range 12 Extensions and Options 11 12 13 14 15 16 17 18 Recal SETUP STNDRD 041027 041028 050228 Fig 3 1 Standard set up ES 0004L 0005L 0006L 0007R 0008R 0009P 0010B 00115 3 3 3 4 Units dB or engineering units Correction on off Printer Language Instrument identification Option 11 Mode dependent parameters The parameters which are not global can be adjusted in one mode of operation for the instrument without affecting the value of the same parameters in another mode of operation If you close a mode and return to it later the value last used for the parameters will be automatically loaded Standard set up Some standard set ups are delivered with the instrum
31. g acoustic parameters according to the International Standard ISO 10052 2004 12 Acoustics Field measurement of airborne and impact sound insulation and of service equipment sound Survey method Measurements according to this standard are made in octave bands Option 1 Octave frequency analysis is therefore required The procedure described in the International standard specifies how to measure sound insulation by measuring levels in octave bands and estimating the acoustic absorption reverberation time The mode is entered by pressing MODE and select 4 SurveyBA See Figure 5 1 The screen shown on Figure 5 2 will then be displayed Press 1 or 2 for selecting the measurement of either airborne or impact sound insulation For measurement of fa ades use Airborne as described in section 5 4 Facade insulation Service equipment sound is measured in the normal mode of operation see 5 5 Service equipment sound At any stage except in result display the instrument may be brought back to normal operation by pressing again and select the mode Normal If you want to change from Airborne to Impact task you have to enter through the general MODE menu Figure 5 1 18 Extensions and Options 11 12 13 14 15 16 17 18 Meas task 1 Airborne 2 Impact Fig 5 2 Menu for measurement task 5 2 5 2 1 5 2 2 Although it is possible to start measurements within t
32. ger is selected the measurement will start immediately after the START key is pressed This corresponds to the way of operation before the trigger option was installed Clock trigger Move the field cursor to Clock then press 1 to select the menu for setting the time for starting the measurement The display shown on Fig 9 3 will be shown Use the Left Right cursor keys to select the field for hour minutes or seconds Modify the value by using the Increase and Decrease key on the right side of the display or key in a numeric value followed by pressing ENTER When the required time is set press ENTER twice for leaving the menus For making a measurement press the START key A Wait indicator i will be shown in the display instead of the Run indicator When the displayed time of the day as indicated by the clock in the instrument coincides with the triggering time a measurement will be automatically started If you want to interrupt a waiting for trigger operation press the STOP key Trig LvlA Threshld 45 0 Freq Netw 1 0kHz dB Fig 9 4 Setting the level for the threshold trigger 9 2 3 9 2 4 Norsonic Nor118 61 User Guide If you set the repeat measurement store function Press SETUP 1 the instrument will start a new measurement after the firs
33. h the method specified in ISO 717 2 for octave band levels The reference curve is shifted in one dB steps until the unfavourable deviations between the octave band results and the reference curve is as large as possible but not more than 10 dB Impact excitation The impact sound shall be generated by the standard tapping machine as specified in ISO 140 7 Measurement of sound insulation in building and building elements Part 7 Field measurement of sound insulation of floors For isotropic floors a single position for the tapping machine near the middle of the room is sufficient See ISO 10052 for further details We recommend the tapping machine Nor211A Measurement of sound level As stated in the standard the spatial average of the sound level in the room may be achieved by measuring the level while moving the sound level meter microphone in a figure of eight trajectory Recommended measuring time is 30 seconds 24 Extensions and Options 11 12 13 14 15 16 17 18 5 3 4 5 3 5 We recommend making the level measurement in the normal mode of operation and storing the result for later processing Alternatively the measurement may be started from the calculation menu when the result is required for the calculation The default set up for the measurement time is 30 seconds but may be set to other values If more positions of the tapping machine are used the mean value may be obtained by pressing CONT after the fi
34. he calculation Building Acoustic Survey program it is in general recommended to do the measurements in Normal mode of operation for the instrument and recall the results to obtain the calculated results This procedure gives better access to the parameters controlling the measurements Airborne sound insulation General The airborne sound insulation is normally measured between two rooms one being the source room and the other the receiver room A stationary sound field is generated in the source room by a suitable loudspeaker If a facade is measured the loudspeaker is placed outdoors and the outside of the building is then acting as the source room The description made here refers to the sound insulation between rooms but may also be adapted to the measurement of facades See section 5 4 Facade insulation Terms and definitions The following terms are used in the display L average sound pressure level in the source room dB L average sound pressure level in the receiving room dB T reverberation time s To reference reverberation time equal to 0 5 s k reverberation index dB D r standardised level difference dB D normalised level difference dB R apparent sound reduction index dB V volume of the receiving room m 5 2 3 Norsonic Nor118 19 User Guide S area of the partition between the source and receiving room m Ay reference absorption area equal to 10 m The relations between the quanti
35. his may be achieved by measuring the level while moving the sound level meter microphone around in a figure of eight trajectory Recommended measuring time is 30 seconds We recommend making the level measurement in the normal mode of operation and storing the result for later processing Alternatively the measurement may be started from the calculation menu when the result is required for the calculation The default set up for the measurement time is 30 seconds but may be set to other values Press SETUP to enter the menu Measurement of reverberation time As required in the referred standard ISO 10052 the corrections for the acoustic absorption may either be based on measurement of the reverberation time or based on estimation based on room type type of surface and furniture Both methods are implemented If a measurement is required we recommend making the reverberation measurement in the reverberation mode of operation and storing the result for later processing MODE 2 Rev Alternatively the measurement may be started from the calculation menu when the result is required for the calculation Calculating the result Select 1 Airborne in the display shown on Figure 5 2 Enter the value for the room volume V and press ENTER or move the field cursor to C and press ENTER for a calculator See Figure 5 3 The calculator allows you to enter the length width and height of the room in order to calcu
36. in If you want to interrupt a waiting for trigger operation press the STOP key Level above trigger The level above trigger function allows a measurement to be started as soon as the level in the specified network or filter band is above a specified threshold In this way a noise event may initiate a measurement The duration and time resolution of the measurement are 62 Extensions and Options 11 12 13 14 15 16 17 18 set as usual The selected main time constant F S or I is used for the level triggering function Move the field cursor to the field Lvl above as shown on Fig 9 2 and press 1 for selecting the threshold A menu as shown on Fig 9 4 is displayed The field below Threshld indicates the sound pressure level needed for triggering Modify the value by using the Increase and Decrease key on the right side of the display or key in a numeric value followed by pressing ENTER When the required level is set move the field cursor to the field below Freq netw Select the require frequency band or network by using the Increase and Decrease key on the right side of the display The networks may be selected by scrolling above the highest frequency band Press ENTER repeatedly until the main measurement display appears For making a measurement press the START key A Wait indicato
37. ion frequency Constant or slightly reducing values in a column indicate the presence of noise Large reductions indicate that reverberation is the main effect Values that first reduce and then increase with increasing modulation frequency indicate the presence of periodic or strong reflections which may produce an over optimistic conclusion It is recommended that if this effect is detected it should be reported with the results and an estimated correction applied 48 Extensions and Options 11 12 13 14 15 16 17 18 6 8 6 9 Limitations of the STIPA method The STIPA method should not be used for those public address systems that a Introduce frequency shifts or frequency multiplication b include vocoders i e LPC CELP RELP etc c have a background noise that is impulsive d introduce strong non linear distortion components If d applies or possibly applies the full STI method should be used instead or used to verify the results obtained by the STIPA method Using Excel for further calculations An Excel workbook STIPA Calc is delivered with the STIPA option The workbook allows you to correct your readings for different speech levels and levels of background noise similar to the corrections available in the instrument Recall the stored results from an earlier measurement Press the button TBL to display the speech level and enter the levels into the cells for the speech level Press TBL once more
38. judged About 15 seconds after the start of measurement the STI value will be indicated on 6 2 6 2 1 6 2 2 Norsonic Nor118 37 User Guide the screen of the instrument No cable is needed between the excitation and the instrument CIS The instrument will use the measured STI value and also present the speech intelligibility in an alternative scale called Common Intelligibility Scale abbreviated CIS This scale is according to the definition in IEC 60849 1998 02 Sound systems for emergency purposes It is a non linear relation between the STI and CIS value although both use 1 to indicate the best intelligibility and O for the poorest Units included in delivery Software option for Nor118 The STIPA calculation program is designated as option no 13 on the Nor118 The option may be activated when the instrument is first delivered or installed on the sound level meter at a latter date Please contact your local Norsonic dealer or the factory if you want your instrument upgraded with this option The STIPA option requires the following additional option to be installed in the sound level meter e N 118 01 1 1 octave real time filters in the frequency range 8 16 000Hz CD for excitation The CD type Nor1034 included with the STIPA option contains two tracks Track 1 and 2 e Track 1 1 kHz sinusoidal signal Duration 2 minutes e Track 2 STIPA excitation signal male speech Duration 70 minutes 38 Extensio
39. l Development of STI The basis for the STI index is that the intelligibility of speech is largely based on the slow modulation of the strength of the sound pressure signal that acts as a carrier In the STI method the carrier is a stationary gaussian noise signal divided in seven bands in octave steps ranging from 125 Hz to 8 kHz The bandwidth of each band is one half octave Each of 33 34 Extensions and Options 11 12 13 14 15 16 17 18 the bands is modulated with one of 14 modulation frequencies The modulation frequencies are selected in one third octave steps from 0 63 Hz to 12 5 Hz This gives in total 98 combinations In the STI context the square of the sound pressure is called intensity The intensity is the quantity being modulated A small loudspeaker playing the modulated excitation signal acts as a talker The sound in the listener position is received by a microphone The level and the degree of modulation in each octave band is used to determine the speech transmission index Noise and reverberation in the room will reduce the observed degree of modulation The method also considers the effect of the most common types of distortions such as harmonic distortion and intermodulation Some other forms of non linearity like frequency shifts and frequency multiplications are not treated effectively In order to fully take care of the effects of non linearity it is important that the basic signal being modulated is
40. laced behind the indicated value for STI and CIS The speech level for each octave may be displayed by pressing TBL A second press on the TBL button displays the modulation indexes for each of the STIPA octaves The combined value for the double octave 125 Hz and 250 Hz is listed as 250 Hz 44 Extensions and Options 11 12 13 14 15 16 17 18 040302 0001S STI 0 62 GO O d CIS 0 79 LA 53 3 NCorr Fig 6 7 When stored a file number shown in the upper line is automatic ally assigned to the measurement STI 0 62 GO O d CIS 0 79 LA 53 3 NCorr STI 0 38 Poor CIS 0 58 BIS Fig 6 8 Correction for background noise 6 4 6 6 4 7 The number below each octave frequency is the modulation frequency in Hz The corresponding uncorrected modulation index is displayed to the right Press the key TBL again to display the highest frequencies Press the TBL button once more for return to the main display NOTE We recommend that from time to time you test your CD player loudspeaker and sound level meter under close to ideal conditions Such a situation exists just in front of the loudspeaker placed in a large room when the background noise is considerably lower than the excitation signal Adjust for a level between 60 and 70 dB In this case you should obtain a STI value close to one Store and recall the result After the measurement is p
41. late the volume After the volume is entered the field cursor automatically moves to the next parameters to be entered Area S Enter the value or use the calculator Estimate k Room type Furnished Kitchen Bathroom Unfurni sh BIS Fig 5 4 Estimating the correction for the acoustic absorption Results 1 1 oct Ri 125Hz 41 6 250Hz 48 4 36 8 22 2 Fig 5 5 Display of measurement result Norsonic Nor118 21 User Guide The field cursor automatically moves between the fields as values are entered If you want to adjust any previously entered value use the arrow keys to move the field cursor to the required parameter The next set of values to be entered is the sound levels in the source room L1 for each octave band Recall a measurement by using the key or press for starting a measurement The values are automatically stored The sound level meter should be moved as specified in the measurement standard to obtain the spatial average The set of levels in the receiver room L2 is obtained in a similar way The acoustic losses of the receiving room used in the calculation may be obtained by measurement by recalling measured value or by estimation The instrument must be equipped with the option for reverberation time measurement in order to allow the measurement option to be used If the optional noise generator is installed it may be used for the excitation other
42. loudspeaker is acting as a talker The loudspeaker should be placed in the normal position for a talker either using or not using a public address system as required The level should correspond to the normal level for speech The signal to the loudspeaker is obtained by playing the audio CD Nor1034 supplied with the recorded excitation signal Place the Nor118 sound level meter with the STIPA option installed and selected in the place where you want the speech intelligibility to be 6 3 2 6 4 6 4 1 Norsonic Nor118 41 User Guide measured Press the START button After about 15 seconds the estimated STI value and the corresponding CIS value is indicated on the screen Selecting a loudspeaker for the excitation Most applications of the STIPA method require a loudspeaker to act as a talker In this case the directivity of the loudspeaker should be close to the directivity for a real human speaker as speech intelligibility depends upon the directivity of the source therefore a mouth simulator having similar directivity characteristics to those of the human head mouth should be used for the highest accuracy when assessing the intelligibility of un amplified talkers Further the frequency response between 100 Hz and 10 kHz should be flat The loudspeaker should be a single element design or using coaxial element so the acoustical centre is well defined IEC 60268 16 recommend using a loudspeaker with a cone
43. matically each day at the same time Similarly the measurement may be initialised by a trigger signal from an external device When started the measurement will last as long as set up by the measurement duration parameter By using the storing option Repeat a new measurement may be started by a new trigger signal after the first is finished The external trigger option may be used for synchronising more sound level meters An often used trigger function is the threshold trigger which starts a measurement as soon as the noise level exceeds a pre defined level Used in combination with the repeat function and automatic storing of the result the sound level meter may unattended store a number of noise events for later analysis 60 Extensions and Options 11 12 13 14 15 16 17 18 Fig 9 3 Setting the time for the clock trigger 9 2 1 9 2 2 Setting the trigger condition When the Nor118 has been upgraded with the trigger option the Trigger Menu is found in the Setup menu see Fig 9 1 Press SETUP and 6 for Trigger The menu shown on Fig 9 2 is displayed The first four lines in the menu allow you to select the function for triggering The last line allows you to set the parameters associated with the selected function Use the Up Down cursor keys below the display to select the desired trigger function Press Enter to confirm the selection Manual trigger When MANUAL trig
44. n should not be used as a replacement for a real measurement of the STI value Specifications The STI value is measured according to the requirements for STIPA method defined in IEC 60268 16 Ed 3 0 2003 05 Sound system equipment Part 16 Objective rating of speech intelligibility by speech transmission index The method specified in the International standard is extended with the option for background noise correction The CIS value is calculated from the STI value as specified in IEC 60849 Ed 2 0 1998 02 Sound systems for emergency purposes 51 Norsonic Nor118 User Guide 7 FFT measurement mode Option 14 7 1 Surve VBA STIPA 7 2 Fig 7 1 The FFT mode is select ed in the mode menu 7 3 Introduction When the FFT option is installed the instrument may make a narrow band frequency analysis of the input signal and calculate the auto spectrum The signal is sampled with a sampling frequency of 24 kHz and a Fast Fourier Transformation based on 2 16384 samples is performed This allows the signal to be analysed with a constant frequency resolution of 1 46 Hz The signal strength may be displayed in logarithmic dB or linear units engineering units EU How to select the FFT mode To put the instrument in FFT mode of operation press the key MODE and select 6 for FFT If you want to return to the normal mode of operation you have to press the key MODE again and select 1 for N
45. n this description as this requires simultaneous measurement in and outdoor However this can be achieved by using two Nor118 sound level meters or a dual channel system such as the Nor121 Please contact your local Norsonic office for further information on such systems Terms and definitions The following terms are used in the display L sound pressure level 2 m in front of the facade dB The term is designated L m in ISO 10052 L average sound pressure level in the receiving room dB T reverberation time in the receiving room s To reference reverberation time equal to 0 5 s k reverberation index dB Fig 5 8 Sound excitation for facade measurement 5 4 3 Norsonic Nor118 27 User Guide Dr standardised facade level difference dB The term is designated D rr in ISO 10052 D normalised facade level difference dB The term is designated Din in ISO 10052 V volume of the receiving room m Ay reference absorption area equal to 10 m The relations between the quantities are given by the following equations k 210 dT T Dr L L k EE The values are calculated for each octave band For D r and D a single number value is also calculated The value corresponds to the value for the reference curve after shifted it in accordance with the method specified in ISO 717 1 for octave band levels The reference curve is shifted in one dB steps until the unfavourable deviations between the octa
46. nd number k corresponding to a specified background noise level If not used this value is Zero lam is an intensity in octave band number k used to mimic the masking effect in the auditory organ The value is a function of the level in the adjacent lower octave band An alternative to keying in the levels for the background noise is to use values from a previously stored measurement The measured levels must have been made in 1 1 or 1 3 octave bands Press RECALL while the table for the background noise is displayed Select the requested file from stored results and press ENTER to read in the data Values measured in 1 3 octave bands are recalculated to 1 1 octave values Real background noise If a real background noise is present during the measurement the effect of the noise will in most cases be treated as noise according to the STIPA method and lower the STI value However some noise signals may be interpreted as a STIPA excitation signal giving wrongly a modest STI value The instrument is programmed to detect such situations and place a question mark adjacent to the indicated value However not all cases can be detected properly To investigate such potential problems we recommend making a measurement without an excitation signal If this STI value is low or considerably lower than the value measured with the 6 6 6 7 Norsonic Nor118 47 User Guide excitation signal preferably STI x
47. nic Nor118 User Guide 8 Reference Spectrum Option 15 Fig 8 1 Frequency mode menu 8 1 8 2 General The Reference Spectra feature is used for comparison of any measured frequency spectrum with a pre selected user defined spectrum It functions both on 1 1 octave and 1 3 octave spectra Alternatively the measured spectrum may be compared to an upper a lower or both an upper and a lower user defined boundary spectra If the measured spectrum exceeds the boundaries a NoGo warning may be given The Reference Spectra features will be available when option 15 is installed in a Nor118 instrument equipped with internal software version 2 0 or newer This option requires that at least option 1 1 1 octave filters is present Activating the Reference Spectrum features The Reference Spectrum features are controlled from the lower part of the Setup menu point 4 Freq Mode see figure The basic requirement is that the Freq Mode is turned On in the upper part of the menu In the lower part of the menu either the Upper or the Lower or both must be turned On These selection will turn on the currently stored upper and or lower Reference Spectra in the graphical level vs frequency display The upper and or lower spectra are displayed using short lines for each individual frequency band The lines are of XOR type which means the lines will always be visible both with and without the actual overlayed bargraph See
48. nnnnnnnnnnnnannnnnannnnnnnn 63 4 Extensions and Options 11 12 13 14 15 16 17 18 10 1 10 2 10 3 10 4 11 11 1 11 2 11 3 12 12 1 12 2 12 3 12 4 12 5 Geral iia 63 Select AGC Out EE 63 Selecting noise type a a 64 Extension for reverberation Measurement cscsccscesecscssscscsssscsscsscscesscscsscescsscssssssscsssssssssssesssssssssssesssssssesssssesseseesees 65 Self noise Compensation Option 18 uessnnannsnannnnnnnnnnnnnnnnannnnnnnnnnnnnnnnnnnnnannunnnnnnnnnnnnnnnnnnnannn 67 LE 67 NAZI NODE EE 69 Measuring the self Noise eerte pe roe te else uester Sine n o PESE Ee 69 Extensions and Corrections to Nor118 User Guide November 2002 71 Algun ai 71 Measurement of reverberation time seseeserseenusnesnsnnesnsnnnsesnunsernnsnsnansennusnesnssnnsusnansesnussesnsssssnssasssssassesnnssssnssassnsnansennen 71 Cad a 72 Store and recall of SEEUPTNOFMAION eege eege 73 PERRA ELIO E E aE E E E E E a 74 1 Norsonic Nor118 User Guide Introduction Software version 2 0 contains many new features like Engineering units Mode related set up Extended list of options The measurement capabilities of the Nor118 sound level meter depends largely on the options installed in the instrument This user guide is applicable for software version 2 0 and describes new features inclusive the following options e Remote Building Acoustics Option 11 e Building Ac
49. ns and Options 11 12 13 14 15 16 17 18 Both signals have the same A weighted level Track 1 may therefore be used for test or calibration purposes although the noise signal is recommended The STIPA excitation signal consists of bands of random noise each modulated with two frequencies See IEC 60268 16 for further details Note that if a loudspeaker is used for excitation the loudspeaker s frequency response may change the spectrum of the excitation The sound level meter may be used to verify or adjust the spectrum For an excitation signal with A weighted level Lx the various octave bands should have the following levels Octave band levels for male speech signal of A weighted level Lx 125 Hz 250 Hz 500 Hz 1 kHz 2 kHz 4 kHz 8 kHz Lx 2 9dB Lx 2 9dB Lx 0 8dB Lx 6 8dB Lx 12 8dB Lx 18 8dB Lx 24 8dB Octave band levels for male speech signal of A weighted level 66 dB 125 Hz 250 Hz 500 Hz 1 kHz 2 kHz 4 kHz 8 kHz 68 9 dB 68 9 dB 65 2 dB 59 2 dB 53 2 dB 47 2 dB 41 2 dB 6 2 3 Printed Instruction manual 6 2 4 A printed version of this manual is a part of the option CD with Excel sheet and Instruction manual The CD contains a copy of this instruction manual in PDF format The CD also contains two Excel work books to be used with a PC e STIPA Calc Allows correction of the STIPA result for a virtual background noise e STI Calc A sheet for es
50. o back to the menu for calculation press ENTER Press the MODE button if you want to return to normal mode of operation Note that you have to be in the menu for entering values before you are able to select another mode Store and recall You may store the result by pressing STORE The file is automatically designated with the next free file number suffixed with the letter B indicating building acoustics Service equipment sound pressure levels See ISO10052 as this specifies how to measure service equipment sound pressure level Option 12 has no special facility for this measurement However the service equipment sound pressure level may be measured in Norsonic Nor118 31 User Guide the normal mode of operation and the values specified in the standard may be calculated The standard specifies how the sound level in a corner position and in the reverberant field is averaged The first level shall be weighted with 1 3 and the second level with 2 3 For equivalent levels Lacg and Lceg this may be achieved by selecting a measurement duration corresponding to the required measurement time for the corner position Make the measurement by pressing START Thereafter move the sound level meter to the position in the reverberant field and press CONT for prolonging the measurement period When the measurement is ended press CONT a second time The result will then have the required spatial weighting 1 3
51. o terminate a key in 10 4 Norsonic Nor118 65 User Guide e Gen switches the signal generator on off e If Sync is on and Gen is off the signal will be switched on when a measurement starts and be switched off after the measurement is ended This is used for reverberation measurement with noise excitation e The noise type may be selected white or pink A pink noise will have similar levels in all fractional octave bands within the main frequency range for the generator 16 Hz 20 kHz e Gain is used for setting the signal level The figure indicates dB relative to 1 volt for the broadband signal Press ENTER to leave the menu after set up Extension for reverberation measurement When the instrument is equipped with option for measuring reverberation time Option 9 the noise generator may be used for the excitation The setup is done in the noise control menu as shown on Fig 10 3 e The excitation type Ex type may be selected impulse IMP or noise NOS e The Excitation time Ex time indicates number of seconds for the noise excitation For measuring reverberation with noise excitation the generator must be set to OFF and synchronisation to ON as shown in Fig 10 3 in order to allow the generator to be switched on and off correctly Press START to perform the measurement Measurement of reverberation by using impulse excitation is described in the main user guide for
52. one the general sign may indicate any relevant physical quantity All values are still stored as level values This allows even stored results to be displayed as dB or EU dependent on the selected setup when the results are retrieved and displayed The selected format for units either or is indicated in the lower left corner of the screen as shown on Fig 2 1 Selecting Engineering Units The selection between levels in decibel or linear units in EU are selected in the instrument set up menu Press SETUP and select 1 Instr 9 Misc par 6 Units Use the field cursor to highlight or as appropriate and press ENTER repeatedly until you are back in the ordinary display How values are indicated Due to the high dynamic measurement range for Nor118 the measured values displayed in linear units will vary over more than six decades By changing the sensitivity of the instrument calibration the display range may need to cover nearly twelve decades A floating point format for the 7 8 Extensions and Options 11 12 13 14 15 16 17 18 Fig 2 2 The graphical display is left unchanged when engineering units are selected 2 4 linear indicated value is therefore necessary A letter following the numeric value is used for indicating the power of ten exponent The following letters are used f 107 femto p 10 pico n 10 nano u 10 micro m 10 milli k 10 kilo M
53. ormal See figure 7 1 Making a measurement A measurement in FFT mode may be started as a normal level measure ment by pressing the START button If Option 16 extended trigger is installed the same trigger possibilities apply as in normal mode of operation the measurement may be started at a certain time of the day or if the level goes above a certain level The level triggering is based on the normal octave or fractional octave band level The measurement duration may be set as time or as a number of single measurements used to obtain an averaged auto spectrum See figure 7 2 NA indicates the number of single measurements in the averaged value The averaged result is continuously updated on the screen during the measurement The measurement may be stopped before the selected 52 Extensions and Options 11 12 13 14 15 16 17 18 number of periods are reached by pressing STOP The duration of each Meas dur single FFT period is 0 685 s Duration During and after a measurement the result is displayed as shown on 00 00 06 figure 7 3 The upper and lover value of the displayed frequency axis are E ae shown just below the diagram The frequency range may be zoomed or Resolution compressed The compression factor are adjusted in a power of 2 685 ms sequence by cursors keys A Compress and V zoom respe
54. oustics Survey Option 12 e Speech Intelligibility STIPA Option 13 e FFT Option 14 e Reference spectrum with Go NoGo comparison Option 15 e Trigger Option 16 e Noise Generator Option 17 e Self noise Compensation Option 18 Option 19 is used for automatic noise monitoring application It allows infinite measurement duration and contains customised functions for read out formats This option is not described in this manual Contact the factory or your Norsonic representative if you need more information The options may be either ordered and installed in instruments delivered from the factory or retrofitted to earlier delivered units This manual does not describe how to install the options Contact the factory or your Norsonic representative 1f you need more information Chapter 12 covers corrections and extensions related to the main user guide for the instrument For description of the sound level meter Nor118 in general reference should be made to the main user guide for the instrument 5 Norsonic Nor118 User Guide 2 Engineering Units 2 1 2 2 Fig 2 1 Engineering units is indicated by a sign in the lower left corner of the display 2 3 Introduction The Engineering Units feature allows you to recalculate and display the result in physical units e g the sound pressure may be indicated in Pascal instead of decibel In conjunction with other sensors than the usual microph
55. r i will be shown in the display instead of the Run indicator As soon as the level comes above the threshold the measurement is automatically started If you set the repeat measurement function Press SETUP 1 the instrument will start a new measurement after the first is finished and wait for the trigger condition to be satisfied again If you want to interrupt a waiting for trigger operation press the STOP key Norsonic Nor118 63 User Guide 10 Noise Generator Option 17 SETUP Instr Meas dur L t par Freq mod Lvl range Trigger Noise 1 2 3 4 5 6 T 5 Fig 10 1 Setup menu 10 1 10 2 General The Nor118 sound level meter contains a connection for an analogue output signal Normally this signal is used for a replica of the microphone signal By installing program option 17 this output may be used as a signal generator Two types of signal are available either white or pink noise The signal is available on pin 15 on the general I O socket Matching cables with BNC connectors for the noise output are available under part numbers Nor4513 and Nor4514 The option 17 allows noise excitation to be used for measurement of reverberation time if the instrument is equipped with option 9 Reverberation and for measurement of airborne sound insulation Option 12 Note that the contents in each menu will depend on the options installed
56. rections The correction for random response windscreen and preamplifier gain also applies in FFT mode of operation Storing the result The measured spectrum may be stored in the instrument and later retrieved or exported to a PC by using the NorXfer program version 4 1 or newer ordered separately The storing is as simple as in the normal mode of operation A file number is automatically generated The file number for an FFT result starts with the letter F followed by six digits representing the year month and day and a sequence number consisting of four digits The storing may be manual or automatic as in the normal mode of operation Extensions and Options 11 12 13 14 15 16 17 18 Specification for FFT Sampling frequency FFT size Frequency lines Anti aliasing filter Frequency range Frequency resolution Window function FFT function Spectrum unit Averaging Number of averages Trigger Input source Dynamic range Zoom 24 kHz 16384 samples 0 682666 sec 8192 frequency lines 6553 will be available after LP anti aliasing filter Pass band ripple 0 03 dB Stop band attenuation 100 dB 0 9600 Hz 1 dB point Af 1 T 1 46 Hz 24000 2 Hanning Auto spectrum dB and EU Engineering units Linear power averaging 1 to 1028571 Manual External Clock Level above Option Microphone socket 120 dB 80 dB displayed Display function C 1 2 4 8 64 55 Norso
57. reverberation mode indicates building acoustic indicates STIPA mode R B P indicates power mode f indicates FFT mode The number assigned to the set up file is presented on the first line on the display after the store operation If you want to use a stored set up for a new measurement Press RECALL select the SETUP directory followed by the required set up file Note If you have made a measurement you may need to clear the display in order to be able to store the set up information Press EXIT for clearing the values from the current measurement and going back to the initial state for the instrument 74 Extensions and Options 11 12 13 14 15 16 17 18 12 5 As a part of software version 2 x the list of predefined set ups are included The setups are located in the set up folder marked STNDRD See chapter 3 in this manual form further information Printing errors Page 40 In multiple time constant pressing CLEAR will deselect all parameters except the first Page 84 Self noise level line 4 0 dB corresponds to 1 uV IN Norsonic P O Box 24 N 3421 Lierskogen Norway www norsonic com
58. rst measurement instead of START The measurement period will be prolonged with the specified measurement time and the averaged value is obtained directly Measurement of reverberation time As required in the referred standard ISO 10052 the corrections for the acoustic absorption may either be based on measurement of the reverberation time or based on estimation based on room type type of surface and furnishings Both methods are implemented If a measurement is required we recommend using the reverberation mode of operation and storing the result for later processing MODE 2 Rev Alternatively the measured may be started from the calculation menu when the result is required for the calculation Calculating the result Select 2 Impact in the display shown on Figure 5 2 Enter the value for the room volume V and press ENTER or move the field cursor to C and press ENTER for a calculator The calculator allows you to enter the length width and height of the room in order to calculate the volume The field cursor automatically moves between the fields as values are entered If you want to adjust any previously entered value use the arrow keys to move the field cursor to the wanted parameter The next set of values to be entered is the sound levels in the receiver room L for each octave band Recall a measurement by using the RECALL key or press START for
59. s move the field cursor to the field NCorr and press ENTER The field cursor is automatically placed at the lowest octave band 125 Hz Write in the required level for each octave by using the numeric keyboard An E at the bottom of the display indicates numeric keyboard second function and that each entry has to terminated by pressing ENTER Move the cursor field to the next frequency by using the cursor buttons below the display and enter the corresponding level For terminating the edition and returning to the main menu press an additional ENTER The noise corrected values are automatically recalculated The correction is done according to the following equation I Ber t Hrs Ino lam mc y where 46 Extensions and Options 11 12 13 14 15 16 17 18 Note You may obtain the averaged level from different measurement positions by making a normal measurement in the first position then move to the next and press CONT for prolonging the measurement time 6 5 MC is the corrected modulation transfer function for octave band number k and modulation frequency f ES is the measured modulation transfer function as displayed I NE K is the measured intensity in octave band number k Ir EH Sk is the intensity in octave band number k related to the threshold of hearing I i Toe Y MOK is the optional intensity in octave ba
60. ss the RECALL key and use the normal memory operation to choose any previously saved measurement as the new Reference Spectrum By confirming the selection with the Enter key the stored Leq values from the selected spectrum will be entered as the new Reference Spectrum In case a 1 3 octave spectrum 1s chosen as a Reference Spectrum for a 1 1 octave comparison the 1 3 octave spectrum will be re calculated into a 1 1 octave spectrum automatically Choosing a previously measured 1 1 octave spectrum for a 1 3 octave comparison will produce an error message File data has wrong bandwidth Entering a new reference spectrum manually Select one of the four possible Reference curves as indicated above use cursor keys to move the field indicator to the first desired frequency band and key in the correct value for this band using the numerical keys Use 8 3 3 8 4 De 16 125 1k APRW 8 5 Fig 8 4 Comparison between reference and measured spectrum A preview is selected Norsonic Nor118 57 User Guide the cursor keys to move the field indicator to the next frequency band and key in the desired value for this new band Continue this operation until all desired frequency bands are entered It is NOT required to enter values for all bands Only those bands which have a value entered will be displayed on the graph Hence the user has full control of which frequency bands of the Reference Spectra th
61. starting a measurement If measured the values are automatically stored The sound level meter Results 1 1 oct In 125Hz 250HZ 500HZ 1 0kHz 2 0kHz Wetd BIS Fig 5 7 Display of the result for an impulse sound insulation measurement Norsonic Nor118 User Guide should be moved as specified in the measurement standard to obtain the spatial average The acoustic losses of the receiving room used in the calculation may be obtained by measurement by recalling measured value or by estimation The instrument must be equipped with the option for reverberation measurement in order to allow the measurement option to be used If the optional noise generator is installed it may be used for the excitation otherwise impulse excitation has to be used For starting a measurement press START when the field cursor is in the field for reverberation time marked T If you want to estimate the absorption as described in ISO 10052 move the cursor to the field marked E and press ENTER By specifying the type of room and the covering for walls ceiling and floor you are entering data corresponding to Table 3 in ISO 10052 When the required information is specified the cursor will automatically be placed in the field for calculation of the final result If you are satisfied with the values press ENTER or if you want to make any correction move the field cursor to the required field and enter the
62. suitable test loudspeaker in the normal position for the speaker Ifa sound system is being used place the sound source on the axis of the appropriate microphone at the normal speaking distance measured from the lip circle for the artificial mouth or acoustic centre of the loudspeaker and direct it in the normal speaking direction Connect an appropriate CD player to the sound source Set the speech level Switch on the sound level meter and ensure that it is properly calibrated Play track 2 with the STIPA excitation signal and adjust the level to the required speech level normally 60 dB at 1 m from the sound source 66 dB at 0 5 m Alternatively track 1 with the sine excitation may be used both should produce about the same A weighted level After setting the speech level play the STIPA excitation signal on Track 2 during the measurement 70 minutes The standard IEC 60268 16 recommends that the excitation spectrum is correct within 1 dB for the applicable frequency range Select the STI mode The STI mode is one of the modes of operation for the Nor118 instrument By selecting this mode the instrument will automatically be configured for STI measurements For selection press after switching the instrument on and select STI by pressing the numeric button After the selection the instrument is ready for a STI measurement A sign ue a A 6 4 5 3 5 4 4 D 3 Fig 6 5 Display of the speech level octav
63. t is finished and wait for the trigger condition to be satisfied again This will occur at the same clock the following day In this way you may start a measurement at the same time every day The duration and time resolution of the measurement are set as usual j Alternatively if you set the synchro measurement store function Press u the instrument will start a measurement at the pre selected time store the result and start a new measurement The duration of the measurement will be as selected but adjusted so the start of the periods are synchronised with the change of the hour for the real time clock in the instrument Example A measurement with a duration of L hour is started 09 40 The first period will end in due time to start the next measurements 10 00 10 30 11 00 etc External trigger The external trigger function is selected by moving the field cursor to the field External as shown on Fig 9 2 and pressing ENTER After pressing the key the instrument will start waiting for an externally supplied binary voltage signal 3 3 volt CMOS The signal has to be applied to DI 1 pin no 8 on the instrument socket See the main manual for the instrument for further information If you set the repeat measurement function Press SETUP 1 the instrument will start a new measurement after the first is finished and wait for the trigger condition to be satisfied aga
64. the figures on the next pages which shows examples with only the upper 1 1 octave and with both upper and lower 1 3 octave Reference Spectra activated 56 Extensions and Options 11 12 13 14 15 16 17 18 Ref curve 8 3 Upper1 1 Lower1 1 Upper1 3 Lower1 3 Fig 8 2 Reference curve selection menu 8 3 1 Upper 1 1 oct 8 0Hz 16Hz 31 5Hz 63Hz 125Hz 250Hz 500Hz 1 0kHz 2 0kHz BIS a 8 3 2 Fig 8 3 Upper 1 1 octave referece spectrum Selecting the Reference Spectra Selection and or editing of the individual Reference Spectra are done in the Ref curve sub menu This menu is opened by first moving the field cursor into the lower part of the Freq Mode menu and then using the H key to open the Reference parameter menu Four Reference curves or spectra are stored within the instrument 1 Upper 1 1 octave spectrum 2 Lower 1 1 octave spectrum 3 Upper 1 3 octave spectrum 4 Lower 1 3 octave spectrum Choose the desired Reference Spectrum by use of the numerical keys 1 4 A table will be presented containing either empty values for each frequency band or the previously used values for each frequency band The individual values may be viewed by scrolling downwards and values for A C and Z weighting networks are available at the lower end of the tables Using a previously measured spectrum Select one of the four possible Reference curves as indicated above pre
65. ties are given by the following equations Zu T D L L k A T The values are calculated for each octave band For Dr D and R a single number value is also calculated The value corresponds to the value for the reference curve after shifted it in accordance with the method specified in ISO 717 1 for octave band levels The reference curve is shifted in one dB steps until the unfavourable deviations between the octave band results and the reference curve is as large as possible but not more than 10 dB The spectral adaptation terms C and C are also calculated according to ISO 717 1 Noise excitation The applied method requires that a broadband noise be used for the excitation The noise may be generated by the instrument if option 17 Noise generator is installed However it will often be convenient to have no cable between the instrument and the loudspeaker for the excitation This may be achieved by using a radio transmitter for the noise signal contact Norsonic for more information An alternative is to play a 20 Extensions and Options 11 12 13 14 15 16 17 18 Airborne V EAAS mn C T E Calc result BIS Fig 5 3 Airborne sound insulation 5 2 4 5 2 5 5 2 6 music CD with recorded noise Norsonic can supply a CD with the required excitation signal as Nor1033 Measurement of sound level As stated in the standard the spatial average of the sound level in the room is required T
66. timating the STI value based on the speech level background noise level and the reverberation time 6 2 5 Norsonic Nor118 39 User Guide Not included CD player and loudspeaker A CD player and loudspeaker for the excitation is not included in option 13 If you need advice for selecting suitable devices please contact your local Norsonic representative Norsonic can deliver a commercially available small radio with rechargeable battery Tivoli Audio PAL It comes with a jack socket for the excitation signal from the CD player When ordered through Norsonic you will also receive a mounting bracket for mounting the radio on a tripod The diameter of the loudspeaker is about 6 cm and the frequency response is fairly flat from 100 Hz to above 10 kHz It has been reported that the selection of the CD player may influence the measurement We therefore recommend testing new equipment before you start the normal measurement tasks If you supply the excitation signal electrically to the sound level meter BNC Lemo adaptor or cable available or measure close to the loudspeaker you should obtain excellent speech intelligibility ratings 40 Extensions and Options 11 12 13 14 15 16 17 18 6 3 Measurement overview 6 3 1 General instrument description N CD player Fig 6 2 Set up for STIPA The figure 6 2 above shows a typical set up for s STIPA measurement measurement The sound source normally a small
67. tivated only this spectrum is considered for the digital output status The digital TTL output line on pin 1 of the I O socket goes high when the instrument is busy taking a new measurement 1 e in Running or Ended Stopped and until the instrument is ready to take a new measurement i e entering the Waiting for trigger mode again Pin 1 Low 0 Pin 1 High 1 Pin 2 Low 0 Pin 2 High 1 Waiting for trigger to the next measurement Busy with an ongoing measurement Status Go Status NoGo Norsonic Nor118 59 User Guide 9 Trigger Option 16 L t par Freq mod Lvl range Trigger Noise Fig 9 1 Setup menu Manual Clock External Lvl above 1 Trig par BIS Fig 9 2 Trigger menu 9 1 General Noise monitoring often requires operating a sound level meter out in the field for unattended long term measurements The trigger option allows the measurement to start when a selected condition is satisfied The condition may be e A certain time of the day e An externally supplied trigger signal is activated e Level is above a specified threshold By using the clock trigger a measurement may be started at a specified time of the night even if the instrument is set up during daytime The result may be stored automatically the instrument can be picked up later and the results downloaded By setting the storing option to Repeat a measurement may be started auto
68. to obtain the modulation indices and bring the values into the appropriate cells You may then enter values for the background noise and see how this will affect your reading The values from the STIPA measurement may be transferred to the PC by using the serial interface on the instrument A transfer program like NorXfer may be used Fig 6 10 The result may be printed or exported to an Excel sheet An overload will be marked by OL unreliable measurements by a question mark Norsonic Nor118 User Guide Nor 118 STIPA Date File R040302 0001 Speech BGNoise 1 1 oct Mod freq m Ls dB Ln dB 125 Hz 72 4 58 2 250 Hz 70 6 59 3 1 00 00 5 00 EA 500 Hz 61 8 51 6 0 63 94 FLO 92 1 0 kHz 53 7 55 5 2 00 87 10 00 x5 2 0 kHz 47 8 45 5 1 25 98 6 30 sol 4 0 kHz 34 1 38 0 0 80 88 4 00 87 8 0 kHz 27 6 31 9 2 5 592 12 5 68 STI OL 0 56 0 39 Fair Poor CIS OL 0 75 0 59 49 50 Extensions and Options 11 12 13 14 15 16 17 18 6 10 STI Calc 6 11 On the CD with STIPA calc you will also find a program called STI calc This program may be used to estimate the STI value based on information on the octave band levels for speech and background noise and the reverberation of the room also in octave bands The applied formulas assume linearity and that the impulse response for the room is well behaved without significant echoes The calculatio
69. ut then the measurement time has then to be set up beforehand The source level shall be measured 2m in front ofthe facade outside at the centre of the facade element This level is designated Ll As stated in the standard the spatial average of the sound level in the receiving room is required This may be achieved by measuring the level while moving the sound level meter microphone around in a figure of eight trajectory Recommended measuring time is 30 seconds This level is designated L2 Measurement of reverberation time As required in the referred standard ISO 10052 the corrections for the acoustic losses of the receiving room may either be based on measurement of the reverberation time or based on an estimate based on room type type of surface and furnishings Both methods are implemented If a measurement is required we recommend making the reverberation measurement in the reverberation mode and storing the result for later processing MODE 2 Rev Alternatively the measurement may be started from the calculation menu when the result is required for the calculation but then the parameters for the measurement have to be set up beforehand Estimate k Room type Furnished Kitchen Bathroom Unfurni sh BIS Fig 5 10 Estimating the correction for the acoustic absorption 5 4 6 Norsonic Nor118 User Guide Calculating the result Select 1 Airborne in the display shown on Figure 5 2 Enter the
70. value for the room volume V and press ENTER or move the field cursor to C and press ENTER for a calculator See Figure 5 3 The calculator allows you to enter the length width and height of the room in order to calculate the volume After the volume is entered the field cursor automatically moves to the next parameters to be entered Area S Enter the value or use the calculator The field cursor automatically moves between the fields as values are entered If you want to adjust any previously entered value use the arrow keys to move the field cursor to the required parameter The next set of values to be entered is the sound levels in the source room L1 for each octave band Recall a measurement by using the RECALL key or press START to start a measurement The values are automatically stored The sound level meter should be moved as specified in the measurement standard to obtain the spatial average The set of levels in the receiver room L2 is obtained in a similar way The acoustic losses of the receiver room used in the calculation may be obtained by measurement by recalling measured value or by estimation The instrument must be equipped with the option for reverberation measurement in order to allow measurements Ifthe optional noise generator 1t may be used for the excitation otherwise impulse method has to be used For starting a measurement press when the field
71. ve band results and the reference curve is as large as possible but not more than 10 dB Noise excitation The applied method requires a broadband noise to be used for the excitation The noise may be generated by the instrument if option 17 Noise generator is installed However it will often be convenient to have no cable between the instrument and the loudspeaker for the excitation This may be achieved by using a radio transmitter for the noise signal contact local Norsonic office for more information An alternative is to play an audio CD with recorded noise Norsonic may supply a CD with the required excitation signal as part number Nor1033 28 Extensions and Options 11 12 13 14 15 16 17 18 Airborne V MEX N C T E Calc result BIS Fig 5 9 The menu for airborne sound insulation is also used for face measure ments 5 4 4 5 4 5 Normally the loudspeaker is placed on the ground in a position which makes the angle between the normal to the facade and the sound incidence close to 45 The distance from the loudspeaker to the centre of the test specimen shall be at least 7m This may be obtained as shown on Fig 5 8 if d is at least Sm Measurement of sound level We recommend making the level measurement in the normal mode of operation and storing the result for later processing Alternatively the measurement may be started from the calculation menu when the result is required for the calculation b
72. wise impulse method has to be used To start a measurement press START when the field cursor is in the field for reverberation time marked T If you want to estimate the absorption as described in ISO 10052 move the cursor to the field marked E and press ENTER By specifying the type of room and the covering for walls ceiling and floor you are entering data corresponding to Table 3 in ISO 10052 When the required information is specified the cursor will automatically be placed in the field for calculation of the final result If you are satisfied with the values press ENTER or if you want to make any correction move the field cursor to the required field and enter the corrected values When you move the field cursor to the field Calc result and press ENTER the following functions are calculated for each of the octave bands 125 Hz to 2000 Hz e The normalised level difference D e The standardised level difference D r e The apparent sound reduction index NI e The source room level L 22 Extensions and Options 11 12 13 14 15 16 17 18 5 2 7 5 3 5 3 1 e The receiver room level L e Thereverberation index E e The reverberation time T For the values D Dnr and RI a frequency weighted value according to ISO 717 1 is also calculated together the correction terms C 25000 marked as C and Cy 125 2000 marked as Cy Pressing the FUNC key repeate

Nor-118 User Manual Extension V2

Contents

Download Pdf Manuals

Related Search

Related Contents