Digital Ears Manual
Contents
1. 10 11 12 13 14 Set the input recording level Turn on the VU meters by selecting VU on the button under the disabled meters Turn the gain adjustment knobs on the front of the Digital Ears counterclockwise as far as they will go e Slowly turn the gain adjustment knobs clockwise until the bars of the VU meters start to light up e Play part of the sound passage you wish to record e Adjust the knobs until the VU meters read roughly between 2 and 0 dB Choose the New option from the File menu Hit the Record button The NeXT will prepare for recording and when everything is ready to go the Pause button will light up Hit the Pause button to begin recording Hit the Stop button to interrupt recording The Stop button also interrupts playback Press Play to play the currently active sound Select Save Save As or Save To from the File menu to save the sound Introduction What is the Digital Ears The Digital Ears is a high speed high precision analog to digital converter with input filters Its compact disk guality input mirrors the NeXT Computer s compact disk guality output and fulfills the NeXT Computer s potential as a powerful environment for sound recording and data acguisition The Digital Ears takes line level audio signals and converts them to digital information in true CD format 16 bit 44 1 kHz stereo It then transmits this informa tion to the dig2. DSP The NeXT Computer s Digital Signal Processor This processor is specifically designed for digital signal analysis The DSP port refers to the 15 pin connector port on the NeXT cube that allows you to connect peripherals like the Digital Ears to the DSP The DSP port acts as a high speed serial port The NeXT DSP is a Motorola 56001 cut off frequency filter A filter which eliminates all frequencies higher than the cut off frequency For analog to digital conversion the cut off frequency should not exceed one half the sampling rate Hertz A unit of frequency equal to one cycle per second k kbyte A kilobyte equal to 1 000 bytes kHz Kilohertz equal to 1 000 Hertz line level signal A signal in the range typically produced by audio equipment before amplification usually in the range of 5 volts meg mb mbyte A megabyte equal to 1 000 kilobytes or 1 000 000 bytes mHz MegaHertz equal to 1 000 kiloHertz or 1 000 000 Hertz mu law A standardized logarithmic scale useful in compressing dynamic range See CODEC signal The term given to a continuous analog voltage that varies in time that represents a sound soundfile A file on the NeXT Computer which stores binary numbers that represents a sound When we talk about playing a soundfile we mean generating a sound from the information stored in a soundfile When we talk about recording a soundfile we mean taking the information that represents a soun
3. 3 Remember that if you have changed the Digital Ears factory setting to mono rather than stereo the Digital Ears will sample the left channel at 88 2 kHz Since stereo format is Left Right Left Right however this presents no problem mono input will be stored Left Left Left Left Using sndrecord to record laboratory data 1 Start up the Shell or Terminal applications to get a UNIX window 2 Enter the sndrecord command with the appropriate flags see Recording with sndrecord in the UNIX Sound Utilities section Examples of sndrecord sndrecord d test dat Record from Digital Ears Length of recording depends on when you type second carriage return sndrecord d s 882000 test dat Record 882 000 bytes 5 seconds from Digital Ears as soon as the command is entered 24 Laboratory Data Acguisition Flash bulb Subject with Photoelectric eyelid sensor cell Figure 7 Sample lab appl cation Sample lab application 25 S Change the factory settings for laboratory data acguisition or special situations 3 Strip off the soundfile header if you do not require it We suggest you consider retaining the header however since it preserves information about the file s format and thus prevents the proliferation of enigmatic binary data files of unkown format See Appendix C Reading the Soundfile Header Changing the factory settings The Digital Ears factory settings should be co
4. 18 e Donotusesndrecord when MonsterScope SoundWorks or any other application has control of the DSP port NeXT software and the Digital Ears Overview MonsterScope s icon Running MonsterScope MonsterScope MonsterScope is a combination oscilloscope spectrum analyzer application which supports three input chan nels DSP A DSP B and CODEC microphone It may be used to view both waveforms and freguency spectra of data as it enters the NeXT DSP port It can also be used as an alternative to SoundWorks for setting input levels MonsterScope is bundled with the NeXT system software To run MonsterScope you will need e The NeXT Computer booted from a SCSI disk e A Digital Ears connected to the NeXT Computer e MonsterScope an application which should be located in NeXT Developer Demos directory Find MonsterScope with the Workspace Manager Double click on MonsterScope s icon to launch the application In a few moments the Oscilloscope win dow should appear on the screen There are two buttons in the upper left hand corner of the Oscilloscope window labeled DSP A and DSP B These buttons activate the left and right channels respectively of the DSP port Beneath the DSP buttons are several groups of buttons The Inputs group contains buttons which control the AC DC or GND ground mode of MonsterScope You should set both channels to AC mode This initial configuration is shown in Figure 5 on t
5. on when you type second carriage return sndrecord d test snd Record from Digital Ears Length of recording depends on when you type second carriage return sndrecord d s 882000 test snd Record 882 000 bytes 5 seconds from Digital Ears as soon as the command is entered sndrecord s 80120 test snd Record 80 120 bytes 10 seconds from microphone as soon as the command is entered If you encounter problems the most likely cause is that another application which uses the DSP port is currently running such as MonsterScope or SoundWorks If one of these programs is running quit from it and try sndrecord again sndplay simply plays the soundfiles you give as argu ments The specified files must be in standard NeXT soundfile format If you give more than one soundfile as argument sndplay will play the soundfiles in sc quence sndplay filel snd file2 snd lt return gt sndplay splash snd Play soundfile splash snd sndplay splish snd splash snd splosh snd Play soundfiles in sequence UNIX sound utilities 17 sndinfo sndinfo will read a soundfile s header and report the following attributes sizein bytes format 8 bit or 16 bit mu Law or Linear sampling rate 8012Hz 22 5kHz or 44 1kHz number of channels any comments stored in the header sndinfo splash snd Report information about splash snd UNIX shell command Donotusesndrecord as a background process release 1 0 user notes
6. that reads the information from a soundfile header and then strips off the header to create a datafile Reading a soundfile header SNDSoundStruct s int fd fn nz int start int sorcery int size int format int rate int numchannels char comment 256 char buffer 2048 fd open soundfile snd O RDONLY 0 SNDReadHeader fd is start s gt dataLocation pointer to sound data sorcery s gt magic magic soundfile iden tifier size s gt dataSize number of bytes of data format s gt dataFormat format of data rate s gt samplingRate sampling rate of data int numchannels s gt channelCount number of channels that data xepresents strcpy comment s gt info comment string fn creat datafile 0666 1seek fd start 0 while n read fd buffer 2048 gt 0 write fn buffer 2048 now datafile contains the data of soundfile snd Appendix D Reading a soundfile header 33 Glossary A D Analog to digital conversion The process of converting a continuous signal into discrete digital information See Appendix A How Does the Digital Ears Work for more information aliasing A kind of distortion that results from sampling a signal whose frequency is more than half the sampling rate It is manifested by a harsh or grainy sound in the recording boot boot up To turn on a computer and load its operating system byte A un
7. ABILITY AND FITNESS FOR A PARTICU LAR PURPOSE ARE LIMITED IN DURATION TO ONE YEAR FROM THE DATE OF THE ORIGINAL RETAIL PURCHASE OF THIS PRODUCT Even though Metaresearch has taken all possible steps to test the software and review the documentation we make no warranty or representation either express or implied with respect to software its guality perform ance merchantability or fitness for a particular purpose This software is sold as is and as the purchaser you are assuming the entire risk as to its guality and per formance In no event will Metaresearch Inc be liable for direct indirect special incidental or conseguential damages resulting from any defect in the software or its documentation even if advised of the possibility of such damages In particular Metaresearch Inc shall have no liability for any programs or data stored in or used with Metaresearch products including the costs of recovering such programs or data The warranty and remedies set forth above are exclusive and in lieu of all others oral or written express or implied No Metaresearch dealer agent or employee is authorized to make any modification extension or addition to this warranty This warranty gives you specific legal rights and you may have additional rights which may vary from state to state Never use the Digital Ears without its cover Always turn the NeXT Computer off before connecting or disconnecting the Digital Ears U
8. Release 1 0 v2 Metaresearch Inc 516 SE Morrison Suite M 1 Portland OR 97214 503 238 5728 F1 it g a F Digital Ears User Manual Version 1 0 Metaresearch Inc 516 SE Morrison Suite M 1 Portland OR 97214 503 238 5728 Legal Notices Copyright Trademarks Limited Warranty on Metaresearch products Copyright 1989 Metaresearch Inc All rights reserved No part of this manual may be copied without the prior written consent of Metaresearch Inc Digital Ears DE 1 SoundWorks and DEController are trademarks of Metaresearch Inc NeXT is a trademark of NeXT Inc The NeXT logo is a registered trademark of NeXT Inc 30 DAY MONEY BACK EXCHANGE POLICY ON METARESEARCH HARDWARE PRODUCTS If for any reason you are not satisfied with a Metare search hardware product Metaresearch will refund you the purchase price provided that you return that product along with all accompanying hardware software documentation and other materials to Metare search within 30 days of receiving the product This offer does not apply to Metaresearch products that have been modified which have been subject to unusual physical or electrical stress or which have had their serial numbers removed or altered Legal Notices i Warning Authors Illustration and Design Support ALL IMPLIED WARRANTIES ON THE MEDIA AND MANUALS INCLUDING IMPLIED WARRANTIES OF MERCHANT
9. al Ears Frequen filter 35 Hz Figure 6 Jumper settings Frequen filter 20 Hz 28 Laboratory data acguisition Appendices The Digital Ears can serve as a compact disk guality audio input ice Appendix A What can the Digital Ears do The Digital Ears is designed to function in two distinct capacities as an audio input device and as a laboratory grade A D converter Together with the SoundWorks software the Digital Ears can save high guality sound recordings on the NeXT Computer Also since soundfiles created by the Digital Ears software can be incorporated into a user interface using Interface Builder the Digital Ears can be used as a platform for software that incorporates high guality sound input Possible examples include e Digital Recording Studios Since the Digital Ears can take line level audio signals from CD players mixing consoles tuners and tape decks it can be used for tasks involving live recording sound editing digital mixing and digital mastering Audio help and error messages Instead of having traditional text files for on line help programs could include soundfiles that lead a user through a seguence of actions with recorded voices music and sound effects Error beeps could become error messages spoken by the computer Appendices 29 30 Appendices Sound as a conceptual aid Sounds corresponding to specific user respon
10. al Ears is not properly connected to the NeXT The source device is not properly connected to the Digital Ears The source device is not sending any signal The signal is too weak 5 Play part of the sound passage that you wish to record For best results play the loudest part of the passage 6 Adjust the knobs until the VU meters read roughly between 2 and 0 dB The system is now ready to record 12 Using the Digital Ears nn Storage reguirements Length of Recording Input levels Audio sources Things to remember Whenever you use the Digital Ears please remember the following facts High guality sound takes up a lot of storage space on disk The following chart shows how much storage space is required for recordings of various lengths made at various sampling rates Sampling Rate in kHz CODEC 22 05 stereo 44 1 stereo 88 2 mono 1 sec 8 kbytes 88 2 kbytes 176 4 kbytes 5 sec 40 kbytes 441 kbytes 882 kbytes 30 sec 240 kbytes 2 65 mbytes 5 29 mbytes 1 min 480 kbytes 5 29mbytes 10 58 mbytes 5 min 2 4 mbytes 26 46 mbytes 52 92 mbytes When you re recording be sure you have plenty of free space on your disk We recommend that you have at least twice as much space as your soundfile will reguire Disks that are too full can develop unpleasant side effects Before recording with the Digital Ears you must first adjust the input levels This is a delicate but essential operation since
11. ampled at a lower sampling rate to a higher sampling rate The up sampled data will occupy twice as much space as the original data Up sampling is not supported in Release 1 0 See down sampling OOREEN As 4 pr ea lt rit tam stay
12. d and writing it to a file on disk Glossary 35 36 Appendices DERecorder saves soundfiles in 16 bit binary linear format written Left Right Left Right in stereo mode and Left Left Left Left in mono mode Soundfiles are like any other files on the NeXT Computer they can be moved deleted opened or edited In the Workspace Manager double clicking on a soundfile s icon will make the NeXT Computer play that soundfile Soundfile names always carry a snd suffix e g splash snd sampling rate The number of times per second that the Digital Ears evaluates the amplitude of the input signal and generates a number that corresponds to that amplitude Sampling rate is often described in freguency i e 44 1 kHz means 44 100 times per second The higher the sampling rate the more accurate the recording and the more storage space the recording reguires It is an axiom of sampling technology that signals that are greater than half the sampling rate will not be accurately represented by analog to digital conversion The Digital Ears samples both channels at 44 1 kHz which means the upper limit of the frequencies it can represent is about 20 kHz which is also roughly the upper limit of the frequencies that the human ear can detect This is why 44 1 kHz is sufficient for for high quality sound recordings The Digital Ears can also sample one channel at 88 2 kHz up sampling The conversion of data s
13. e Digital Ears can also act either as a two channel 44 1 kHz 16 bit A D converter or as a single channel 88 2 kHz 16 bit A D converter In both cases the Digital Ears can function in either AC or DC mode The Digital Ears data acquisition capabilities have applications in harmonic spectral analysis of signals and other speed and resolution intensive data acquisition tasks in a number of fields Electrical Engineering Physics Signal Processing Biomedicine Normal Mode Analysis Harmonic and Signal Analysis Sampling theory Waveform analysis 0 o o ooo Appendix A What can the Digital Ears do 31 EEE 32 Appendices Appendix B Technical specifications Frequency Response Stereo DC 20kHz 3db Sampling Rate Stereo 44 1kHz d Sampling Rate Mono 88 2 kHz Signal to Noise Ratio Input gain stage 98 db A D stage 85 db Total noise harmonic distortion relative to full scale i 1 KHz sine wave 0 005 A D Input Voltage Range 5V Max Input Voltage Range 8V Input Impedance 100 kOhms Gain Stage Noise Equivalent 25nV JHz 10Hz Lincarity Error DC mode 4 LSB 4 parts in 65 000 Appendix C Timing diagram 0 13 30 6 7 8 9 30 11 12 23 14 35 Ix pin 1 DATA pin 2 ix internal pin Lii tpia 12 Appendix D Reading a soundfile header NeXT soundfiles all contain an SNDSoundStruct header that contains the information about thesoundfile Here is a fragment of C code
14. ements which involves changing the Digital Ears factory settings Second soundfiles on the NeXT Computer have a special format that includes a header When saving laboratory data this header is unnecessary but can be useful if adapted for lab data Setting up your equipment 1 Disconnect the Digital Ears from the NeXT Computer and change the factory settings as needed See Changing the Factory Settings below 2 Connect the Digital Ears to the NeXT Computer 3 Connect the signal sources to the RCA inputs on the Digital Ears You are ready to begin recording data Make sure the signals to be measured are between 8 volts we recommend you use MonsterScope to look at the data coming in to the Digital Ears to make sure that levels are appropriate Remember that you cannot look at data using MonsterScope and SoundWorks at the same time because both applications require access to the DSP driver Setting up your equipment 23 Take care when using the Digital Ears in mono mode A useful convention is to end the names of all data files with a dat Recording laboratory data As in recording sound there are several options for recording laboratory data You can use SoundWorks or the UNIX sound utility sndrecord to create sound and Or data files Using SoundWorks to record laboratory data 1 Start up SoundWorks by clicking on its icon in the Workspace Manager 2 Click the Record button to begin recording
15. he following page MonsterScope 19 Setting Input Levels with MonsterScope Figure 5 MonsterScope settings These are the correct settings for using MonsterScope with the Digital Ears For a more detailed discussion of the issues involved in setting input levels please refer to Setting input levels in Using the Digital Ears To set the input recording levels for the Digital Ears using MonsterScope 1 Make sure the Digital Ears is connected to the NeXT Computer Start up MonsterScope Turn the gain adjustment knobs on the front of the Digital Ears counterclockwise as far as they will go Connect a source device such as a tape deck or a CD player to the inputs of the Digital Ears and make sure itis sending a signal to the Digital Ears Press the DSP A button to activate the left channel and make sure the AC button is on Slowly turn the gain adjustment knob clockwise until you see a signal emerge If you do not see a signal appear the most likely causes are e You haven t turned the knob far enough The Digital Ears is not properly connected to the NeXT The source device is not properly connected to the Digital Ears The source device is not sending any signal The signal is too weak As the signal gets stronger you should see peaks of the signal become flattened at a fixed level this is clipping see Figure 6 Don t worry if you cannot make the signal large enough t
16. ill probably want to change the input filter frequency cutoff mode see next page Figure 5 Jumper locations Default settings 27 Input filter freguency cutoff mode selection The Digital Ears factory setting is 20 kHz both channels The Digital Ears has low pass input filtering to protect users against playback distortion Even in situations where there is no audible need for filtering high fre quency components of signals can produce a kind of dis tortion known as aliasing Since the Digital Ears can run in mono or stereo there is a provision for changing this cutoff frequency of the input filter The two choices are a cutoff of 20 kHz for stereo and a cutoff of 35 kHz for mono To change the cutoff frequency set JP6 according to the table in figure 12 Leaving JP6 open means the cutoff is 20 kHz Closing JP6 changes the cutoff to 35 kHz As a technical matter it is always advisable to ensure that your signal has no strong frequency components near the sampling rate These inaudible components are the cause of aliasing the result being glitches or chirps in your playback One source of Jumper Setting Result aliasing distortion is FM stereo JP1 Left or JP2 Right FRONT FACEPLATE tuner output which may have a 38 kHz stereo pilot tone you cannot hear AC mode If you have signal conditioning equipment you may want to filter your signals before sending them to the Digit
17. in output file filename snd f DSP PROGRAM Run the specified dsp program on the DSP and store the resulting output in the output file w Warn if sndrecord detects an output overflow s SIZE Record SIZE bytes Unfortunately this is the only way you can specify the length of a recording before the recording actually starts If you re reading data from the microphone a 1 second recording will require 8012 bytes If you re reading data from the Digital Ears a 1 second recording will require 176 400 bytes Unlike the others this option starts recording as soon as you enter the command see below After you enter the sndrecord command a message should appear telling you to hit a carriage return to start recording followed by a second carriage return to stop recording If you use the s option you will not get this message sndrecord will start recording as soon as you enter the command and stop when it has recorded the number of bytes you specified 16 NeXT software and the Digital Ears sndrecord examples sndplay syntax sndplay examples When the recordingis finished sndrecord will report the number of bytes recorded and your prompt will reap pear Once a soundfile has been created it can be copied moved or modified like any UNIX file Remember to end your output files with snd so that the NeXT will recognize them as soundfiles sndrecord test snd Record from microphone Length of recording depends
18. ine NeXT documentation UNIX sound utilities If you aren t familiar with UNIX you may want to skip this section To use any of these utilities you should first start up a UNIX shell window using either the Shell or Terminal applications included in the NeXT system software Remember that these utilities are part of NeXT s software release and they are all documented in the on line UNIX programmer s manual For more detailed information double click on the UNIX Manual icon in the Digital Library window and type the name of the command you want to learn about UNIX sound utilities 15 Recording sounds sndrecord can make recordings from the Digital Ears or with sndrecord froma microphone plugged into the MegaPixel display It has a number of powerful options for developers if you just want to make sound recordings however you may find SoundWorks easier to use If it records from the microphone sndrecord sets the sampling rate at 8012 Hz and stores the resulting data in 8 bit mu law format mono If it records from the DSP port i e the Digital Ears sndrecord sets the sampling rate at 44 1 kHz and stores the resulting data in 16 bit linear format stereo sndrecord syntax sndrecord options filename snd lt return gt The options are summarized as follows d Record from the DSP port This is the correct option for recording from the Digital Ears The recording will be stored
19. it of computer memory equivalent to 8 bits Memory and disk space are usually measured in bytes kilobytes 1 000 bytes and megabytes 1 000 000 bytes CD Compact Disk clipping The distortion that results from an input signal whose amplitude exceeds the input tolerance of the Digital Ears This tolerance is 8 volts Ideal recording range is from 0 5 volts to 5 volts CODEC A coding decoding scheme based on a standardized logarithmic scale called a mu law scale CODEC technology is useful for compressing dynamic range For example the NeXT CODEC microphone has 8 bit accuracy but 12 to 16 bit dynamic range because of an internal CODEC processor D A Digital to analog conversion The complement of A D conversion that is the conversion of discrete digital information to a continuous analog signal data acquisition The process of measuring digitizing and sending laboratory data to a computer for subsequent analysis testing or display down sampling The conversion of data from a higher sampling rate to a lower sampling rate For example down sampling from 44 1 kHz to 22 05 kHz involves deleting every other sample from the data and doubling the length of time that the remaining samples represent So sampled data s0 s1 52 53 54 becomes s0 52 54 V SO SS S S S S EE This means the down sampled data will have half the resolution of the original and occupy half as much space
20. ital signal processor DSP on the NeXT Computer What does all of this mean The real world is largely analog that is most phenom ena that we can observe are continuous Consider the arc of an arrow shot from a bow It traces out a smooth curve until it plunges to the earth it does not descend jerkily In the same way when you record a violin solo What is the Digital Ears 1 Computers need digital information Analog representation of signal The Digital Ears changes analog signals to digital signals Digital representation of signal through a microphone the voltage signal it generates consists of peaks and valleys not of staircases But the world of computers is digital no matter how sophisticated a computer must represent signals in discrete numbers This is why you can t just plug a receiver into a computer and expect to get any meaning ful results You must first find some way of converting continuous signals from the real world into discrete digital information that the computer can manipulate Hence the Digital Ears A waveform can be used to represent a sound s loudness and pitch Amplitude volts TIME The sound s amplitude or relative loudness is shown by the height of the waveform Its pitch is represented by frequency or number of peaks per second Frequency is expressed in Hertz one cycle per second is a frequency of one Hertz The lower the frequency the lower the pitch
21. l Ears 1 Turn the NeXT Computer off THIS IS IMPORTANT 2 Connect one end of the Digital Ears cable to the DSP port on the back of the Digital Ears 3 Connect the other end of the cable to the DSP port On the back of the NeXT cube 4 Start up the NeXT Computer The Digital Ears is now active and ready for use Setting up your eguipment Your Digital Ears set up will depend on what you want to do with it If you want to use the Digital Ears as a laboratory data acguisition device please refer to the Laboratory Data Acguisition section There are several different ways to install and use the Digital Ears If you re recording sounds you ll probably want to listen to them at the same time The set up shown in Figure 2 see next page lets you record from several different sources while listening to what you record the set up shown in Figure 3 is intended to illustrate one of the potential uses for the Digital Ears real time voice recognition NeXT Cube Receiver CD Player Speakers Microphones Figure 2 Sound configuration This configuration lets you listen to sounds while you record them Sound configuration Figure 3 Voice recognition This con ation illustrates mm rt Digital Ears potential application areas 10 Introduction See Figure 2 for an illustration of this set up You can set input levels for recording using either SoundWorks or MonsterScope Most
22. o observe clipping but in order to make a recording you will need some signal Deactivate the DSP A button and repeat steps 5 and 6 for DSP B To ensure balance between left and right channels look at both signals simultaneously on MonsterScope s display Press the Identify button 20 NeXT software and the Digital Ears Figure 6a Normal signal Figure 6c Ideal signal for sound recording Signal is completely visible within Signal is clipped when Digital Ears Signal is contained within the middle scope display input levels are set too high third of the scope display for one channel to distinguish it from the other Are the signals the same size You may wish to make some final adjustments to set the balance If balance changes are reguired it is usually best to decrease the larger signal to match the smaller one MonsterScope 1 0 The controls are slower to respond when the DSP User Notes channels are active If you are changing settings it is best to set do it with both DSP A and DSP B inactive e Ifyou want to use SoundWorks or any other program that uses the DSP make sure to turn off the DSPA and DSPB control buttons first MonsterScope user notes 21 2 ss ee EEE Sis 22 NeXT software and the Digital Ears Laboratory Data Acquisition Overview Laboratory data acquisition differs from sound record ing in several ways First laboratory users usually want to take DC measur
23. of the sound The Digital Ears takes an analog signal like the one represented by the waveform above let us say the signal that represents a violin concerto and samples that signal at 44 1 kHz per channel This means that it determines the signal s amplitude at a certain instant and produces a digital value a number that corresponds to that ampli tude Digital Ears repeats this process which is called sampling 44 100 times a second Amplitude volts TIME Once Digital Ears has converted the anaolog signal to a discrete binary number the value is transmitted to the NeXT s DSP chip Software that accesses the DSP can then process the data for analysis display or storage a 2 Introduction Bundled with DE 1 These applications are included with the Digital Ears under release 1 0 Bundled with the NeXT Computer These applications are included with the NeXT system software Each sample is a 16 bit binary number which means that the number of possible values is 2 or 65536 This reso lution is the same as that of a compact disk recording This means that recordings made with the Digital Ears will be faithful reproductions of the original What software can be used with Digital Ears SoundWorks a user friendly digital sound processor which can record and play sounds and prepare soundfiles for inclusion in other applications DEController a C object which facilitates the development of cust
24. om applications that use the Digital Ears DEController includes methods for recording playing opening and saving sound datafiles as well as methods for monitoring the DSP port for incoming data MonsterScope a powerful three channel 44 1 kHz oscilloscope and spectrum analyzer that lets you view data as it comes into the Digital Ears UNIX sound utilities the utility programs for manipulating soundfiles that are included with the NeXT system software UNIX utilies are all documented in the on line UNIX programmer s manual Sound Kit and Music Kit these kits provide software tools for playing editing synthesizing and displaying sound Also they include usable code for controlling the NeXT s DSP chip What software can be used with the Digital Ears 3 Available from e Media Station a software package by Imagine Inc third parties which provides the means to combine and process images sounds and text to create multimedia MediaStation and FrameMaker are applications and presentations two examples of third party applications that use Digital Ears there are many more in devel FrameMaker an application from Frame Technology Corporation which combines sophisticated word processing graphics and layout capabilities with the ability to incorporate sound into documents aa S o a Te a een 4 Introduction Anatomy of the Digital Ears Backplate Gain Adjustment Knobs aan 4 Connec
25. oratory data sess sssssessssessssnsessssse 24 Changing the factory Settings ssesesereeseseeneee 26 PDefaultis tti1gSi n ccescecosnssocssrsossncrncaccnsnssonessnnonsocceses 27 AC DC mode selection eseensossnesssensosenensnensenuneee 27 Stereo mono mode selection ueunsensesnssnsensennseunnen 27 Input filter frequency mode selection 28 Appendices Welcome Welcome to Digital Ears Digital Ears brings high guality sound recording and high resolution data acguisition to the NeXT Computer With Digital Ears and the NeXT Computer high guality sound is about to assume a new and important role in personal computing Thank you for choosing Digital Ears We are always open to suggestions for additions to both our hardware and software If there is a capability you would like to have access to please give us a call Sincerely Jean Delord President Metaresearch Inc Welcome V About this manual Getting Started in a Hurry provides summarized installation and recording instructions for experienced NeXT users who want to begin to use their eguipment immediately The Introduction explains what the Digital Ears is and how it works It also provides a brief description of the software that is available for use with the Digital Ears Using the Digital Ears gives detailed step by step instructions for connecting the Digital Ears to the NeXT Computer and setting up equipment for sound rec
26. ord ing NeXT Software and the Digital Ears describes the utility programs for recording and manipulating soundfiles that are included with the NeXT system software This section also discusses MonsterScope an oscilloscope application bundled with the NeXT software Laboratory Data Acquisition explains how to use the Digital Ears as a laboratory grade analog to digital converter It also explains how to change the Digital Ears settings to suit your particular requirements The Appendices include a discussion of some potential DE 1 applications a glossary and a description of soundfile formats The appendices also state some technical specifications For more detailed information please contact Metaresearch About this manual vii Preface viii Getting started in a hurry with Sound Works Always remember to turn the NeXT Computer off before connecting or disconnecting the Digital Ears TURN THE NEXT COMPUTER OFF Connect one end of the Digital Ears cable to the DSP port on the back of the Digital Ears and the other end to the DSP port on the back of the NeXT cube Start up the NeXT Computer Connect a source device such as a tape deck or a CD player to the inputs of the Digital Ears Mount the Digital Ears 1 0 optical disk in the NeXT drive Copy the SoundWorks application folder to an Apps directory Double click on the SoundWorks icon to open it Getting started in a hurry ix
27. receivers have a tape monitor button by connect ing the NeXT Computer to the Tape In PLAY jack and the Digital Ears to the Tape Out RECORD jack on your receiver you can monitor levels the same way you would with a tape deck The only drawback to this approach is that there is some degradation of signal guality as the signal is routed through the various components and cables To set up your eguipment for sound record ing and playback Connect the Digital Ears to the NeXT see Installing the Digital Ears above 2 Connect the Tape Out Record jack on the back of the receiver to the Input jacks of the Digital Ears 3 Connect the Tape In Play jacks on the back of the receiver to the Line Out jacks on the back of the Megapixel display 4 Connect the sources outputs to their corresponding inputs on the receiver 5 Make sure that the speakers are connected to the receiver 6 Play some music on the system to test the connections Setting input levels using SoundWorks Make sure the Digital Ears is connected to the NeXT Computer 2 Start up SoundWorks 3 Turn the level adjustment knobs on the front of the Digital Ears counterclockwise as far as they will go Set up for sound recording 11 4 Slowly turn the level adjustment knobs clockwise until the bars of the VU meters start to light up If the meters do not respond the most likely causes are You haven t turned the knobs far enough The Digit
28. rrect for most sound recording needs but for laboratory data acguisition or for special situations you may want to change them To change these settings you will have to manually reset jumpers on the Digital Ears circuit board Always disconnect the Digital Ears from the NeXT Computer and from any inputs before removing the cover To change a jumper setting 1 Turn off the NeXT if it is linked to the Digital Ears 2 Disconnect any inputs to the Digital Ears 3 Remove the two silver Philips head screws on the bottom of the Digital Ears case 4 Slide out the circuit board by pushing on the front faceplate and place it on a hard flat surface 5 Locate the appropriate jumper in Figure 5 and set it according to the table in Figure 6 26 Laboratory data acquisition Default settings AC DC mode selection Stereo mono mode selection The Digital Ears default factory settings are e AC mode both channels e Stereo mode e Input filter frequency cut off at 20 kHz both channels The Digital Ears factory setting is AC mode in both channels To change AC DC mode set jumpers JP1 and JP2 according to the table in Figure 12 The Digital Ears factory setting is stereo To change stereo mono mode set JP3 according to the table in Figure 12 When the Digital Ears is in mono mode the left channel becomes the mono input and the sampling rate becomes 88 2 kHz If you change this mode you w
29. se of controls or adjustments or operating the Digital Ears in any manner not specified in this manual voids the manufacturers warranty Juliette Guilbert Chris Lydgate and Andy Laird Marianne Colgrove and Juliette Guilbert Kim Orumchian Contents Preface W lcd0fi iacesnisss ss oss A ss v About this mM ntt li su usa as asas S vii Getting started in a hurry with SoundWorks ix Introduction What is the Digital Ears ssccscssssssssssserseeessersenees 1 What does all of this mean essssssssssesessessssese 1 What software can be used with the Digital Ears c ccscscscsscesssesereecseesvecnsocese 3 Anatomy of the Digital Ears s serseseseeneeeeenees 5 Using the Digital Ears WYRE IIE SEE immensen een 7 Precautii sscscserscsscisssseccicocerscossstcnsisosneensccesnivanchersies 8 Installing the Digital Ears sssssssssesneerenseneens 8 Setting up your equipment usssssesssenennensensenennsenen 8 Setting lnpitlii bs css r 11 Things to remember u ssssessssisnesssinsssissennesseneeniisen 13 Contents iii NeXT software and the Digital Ears NTN an E E IA AEE E EA 15 Unpesoumd ATTICS ssemsbsemeumeties remo 15 UNIX sound utilities user notes seccsecesersees 17 MonsterScope nusoemsssosssssnssesnonsersarsensnmnssussennsenne 19 D KE EL o RENNER EEE EETA 23 Setting up your equipment ussssssnensenensenensenenensenen 23 Recording lab
30. ses could reinforce or discourage certain actions A CAD program could groan when a structural member is placed in the wrong position a circuit board layout program could play a different sound whenever a different component is placed on the board Sound as a presentation tool Presentation technology holds great promise for education as well as business and high guality sound is an important part of any presentation A software demonstration could include a recorded narrative complete with background music to explain a slide show With this approach teachers and managers can make more effective demos more guickly than before Music Education There are many possibilities for software that can record play display edit and filter sound A music laboratory could compare the structure harmonic content and other aspects of recordings stored on optical disk or even modify famous masterpieces Voice Recognition Because the Digital Ears sends high guality high resolution data directly to the DSP port software that reads information from the DSP port could perform real time voice recognition Language Laboratories Software could play a phrase for a student record the response and critique the student s pronunciation Medical and Clinical applications Software for the analysis of speech and hearing as a diagnostic tool The Digital Ears can serve as a laboratory grade high resolution A D converter Th
31. the quality of the recording depends on the audio input level See Setting input levels using SoundWorks p 11 or Setting input levels with Mon sterscope in NeXT Software and the Digital Ears The Digital Ears will accept any source of music or sound provided that its output signal is within a range of 8 volts Signals within this range are called line level signals Signals that are too strong such as signals that have been amplified by a power amplifier will be subject to distortion and could ultimately corrupt the system Signals that are too weak such as those pro duced by some microphones must be passed through a pre amplifier before they are fed into the Digital Ears Optimal signal size for input to the Digital Ears is in the 05 to 5 volt range Signals below or beyond these limits will be recorded but the signal to noise ratio may be low Things to remember 13 oo Using the Digital Ears lt ri NeXT software and the Digital Ears Overview NeXT system software Release 1 0 includes several tools for working with sound These are UNIX sound utility programs for manipulating soundfiles MonsterScope an oscilloscope spectrum analyzer and the Sound and Music Kits which provide software tools for playing editing synthesizing and displaying sounds UNIX utilities and MonsterScope are discussed in this section for information regarding Sound Kit and Music Kit please refer to the on l
32. tor to DSP Digital lars R Circuit Board Faceplate Inputs Figure 1 Inside the Digital Ears This exploded view shows the basic components of the Digital Ears Anatomy of the Digital Ears Cover Introduction 6 Using the Digital Ears What you need A NeXT Computer with a hard disk and at least 8 megabytes of RAM e A Digital Ears with connector cable included A line level audio source and a cable to connect it to the Digital Ears NeXT system software release 1 0 We also recommend the supplemental hardware listed below While not essential it will help you get the most out of the Digital Ears e A receiver or pre amp power amp combination for sound playback e A pair of high quality speakers e Several spare RCA male to male patch cables e Additional hard disks A printed copy of the NeXT technical documentation especially the sections concerning the Sound class recording Interface Builder and the SoundKit can be very helpful What you need 7 8 Using the Digital Ears Precautions ALWAYS turn the NeXT Computer off before connecting or disconnecting the Digital Ears e NEVER remove the cover from the Digital Ears while it is connected to the NeXT Computer e NEVER enter speaker amplified output from an audio power amplifier into the Digital Ears The Digital Ears is designed to take a standard line level input only Installing the Digita
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