Audio  Scientific            Audio   Expertise   for  Digital   World
 Telecommunications, Digital and Wireless engineers often addvoice to their design.  It has been proven many times that sound quality depends on designer's approach & skills -and each product sounds differently. Correct conversion of digital signals into analog and sound signals requires a set of critical skills, to ensure high voice quality in the entire chain, end to end,under all conditions and with all settings of software controls.

Audio Scientific provides this critical set of skills.  We take care of all aspects of client design from dBm0 to dBV and dB SPL. We specialize inaudio for telecom, wireless, digital, medical and hand portable products. We coverBluetooth, cellular phones, cordless, telephone handsets,hands - free, headsets, speakerphones with a variety of accessories, echo cancellers, portable audio appliances, electronic book readers, noise canceling microphones plus all products where a chain of sound, analog and digital signals involved or voice capability required.

Experience how easy and stress free will be your job when we take care of the analog end and acoustics. Do not slow down your engineers with audio & acoustical tasks, delegate such tasks to Audio Scientific! Let Audio Scientific expertise in analog design and acoustics work for you. Let us shorten your design time, save you money and faster move your product to market. Compare voice & sound quality before and after we worked with you. See  Engineering Service Examples below,  Audio Scientific -Brochure (pdf 508kB),  PriorAccomplishments (or word doc 65 kB), ask for a free initial consultation at your location or over the phone, learn about our Ultra Low Noise Anechoic Chamber, learn how you can rent acoustical anechoic chamber on daily basis.   Contact燩eter Sobczak, Audio Principal Engineer at   petersob@audioscientific.com.  Audio Scientific, 11463 Tree Hollow Lane, San Diego, CA 92128.
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Acoustics Animations Sound Interactive Demos     Audio Test EquipmentManufacturers &Sources

Acoustical Anechoic Chambers   AutoCalculators& References    Audio Measurement Techniques  

AudioCompression       AcousticalTreatment Materials       Audio Marketplace       Audio Software 

Batteries    Bioacoustics- Ultrasound - Underwater - Wildlife     BluetoothAudio  
Circuit Simulators

ClassD Amplifiers            Data Loggers             Engineering Resources            EMF - Electrosmog

Electronic Circuits - Schematics & Tutorials            Interesting Sound Websites          Microphones

MicrophoneCables               Noise            NoiseCanceling Headphones & Active Hearing Protectors 

NoiseReduction & Intelligibility & Voice Quality & SpeechRecognition      Ultra High End Devices

EchoCancellers Suppressors Hands - Free   Variable Gain Amplifiers (VGA)  Ultra Low Distortion             

Ultra LowNoise     Ultra Low Power      UltraLow Resistance       Ultra Fast Devices    
USB Audio

RoomAcoustics           Sound Cards         Sound Meters          SpecialAudio Companies & Products


 Speakers         Transducers & Headsets&Suppliers           WirelessAudio &  Telecommunications
Engineering Service Examples
Provide access to our San Diego located sound anechoic chamber. Lease termsavailable.
Design appliances with devices like microphones, speakers and buzzers
Conduct Audio Seminars
Setup audio lab at any location of client choice
Design Review
Hardware Design:   dBm0 - dBV - dB SPL - dB Pa
Documentation: Specifications, procedures, design process, manufacturing process
Testing
Test Fixtures
Calculations
Analog Circuit Simulation
Transducer Simulation
Electronic Circuitry Design
Transducers Selection
Dummy Prototype - product with audio transducers, no electronics
Functioning Prototype - product with audio transducers and electronics
Production Support
Provide access to our San Diego located sound anechoic chamber
1. Includes power line isolated setup, with all test setup components powered with individual batteries. We record voice signals down to -3dB SPL "A", 1Hz.
2. Your crew may bring equipment for testing in anechoic chamber and workingon your problem. Our mobile test setup allows automotive tasks like hands-free,speech recognition, echo canceller, echo return loss, audible noiseand more.
Design appliances with devices like microphones, speakers and buzzers
3. Portable audio appliances, laptop, cellular and hands-free phones,speakerphone and more.
4. Build microphone and speaker into housing including computer monitorand car interior.
5. All steps from concept to production: Parts selection, documentation,schematics, drawings, procedures, testing, fixtures, prototypes and calibrationreferences.
Consulting
6. Analyze your needs and prepare custom tailored seminar for yourcrew.
7. General audio, analog circuitry, audio transducers, equipment orclient interest areas presented.
8. Client site or specific case dependent location.
9. Practical tips and answers only audio expert can give.
10. Information about sound nature, sound sources, picking and producingsound, devices and tricks involved.
11. Problem solving skills at expert depth available on 搎uestion andanswer?basis.
12. Audio design, circuitry, transducers, parts selection, testing,troubleshooting, measurement, signal references, sound calibration, testsignals, applying filters, test fixtures and equipment areas.
Setup audio lab at any location of client  choice
13. Select anechoic chamber, sound absorbing materials and equipment.Deal with vendors.
14. Train your crew to use audio test equipment.
15. Design and build specialized test fixtures for general use andfor specific application.
Design Review
16. Review requirements and prepare detailed list of audio design stepsfrom concept to production.
17. Evaluate design progress and propose steps needed to speed it upand move it in right direction.
18. Compare yours and your competitor products in performance and specificationterms.
19. Analyze your problem, find what you need and propose detailed actionlist.
20. Review schematics, mechanical drawings and audio components?specifications.
21. Review environmental requirement for your product and audio components.
22. Confirm 揾earing aid compatibility? 搗oice recognition compatibility?搘aterproof?and  搘eatherproof?requirement for product and components.
Hardware Design:   dBm0 - dBV - dB SPL
23. Analyze end to end requirement, including mixed signal chips, Codecs,sensors and audio transducers.
24. Make sure that signals flow properly, following rules.
25. Create requirement for gain, frequency response distribution foreach functioning block in the chain.
26. Specify or evaluate existing circuit interface compatibility withend devices like speaker, microphone.
27. Create simulation and build devices like loopback fixture, timedelay fixture and more.
28. Digital - Analog - Sound - Microphone & Speaker conversioncalculations.
29. Specify, select and incorporate semiconductors to meet specificgoal.
30. Evaluate, test, troubleshoot and calibrate any portion or entireexisting design, end to end.
Documentation
31. Extract audio requirement from your documents, industry standardsand customer needs.
32. Create requirement and buying list for requirement for engineeringtest equipment with fixtures.
33. Create requirement and buying list for production audio test equipmentand production audio fixtures.
34. Create audio requirement and test procedure for production audiofixtures.
35. Create audio requirement and test procedure for production audiofixtures?transducers.
36. Create audio requirement and test procedure for product designverification.
37. Create audio requirement and test procedure for product system verification.
38. Create level and frequency response limits envelopes, for designand system verification testing.
Testing and recording
39. Measure and record everything that carries sound or audible frequencysignal.
40. Measure and compare yours and your competitor product, specificsegment or end to end.
41. Measure audio transducers like microphones, speakers, ringers,buzzers, and receivers.
42. Measure directionality, distortion, response, level, noise, tolerance,echo, sidetone, many more terms.
43. Incoming inspection, qualification and environmental testing, productiontroubleshooting, engineering prototypes, vendor samples and more.
44. Sound exposure, correcting test results for noise involved, variousfilters and custom-made test signals.
45. Wide range of setup scenario, anechoic chamber to hands-free, frommoving vehicle to flying aircraft.
46. Measure noise created by your product or fixture, evaluate noise reduction progress, provide detailed comparison charts for each design.
Test Fixtures
47. Analyze your product and estimate what fixtures are required.
48. Analyze your problem and propose custom design fixture.
49. Fixture design end to end, including mechanics, electronics, transducersselection, documentation.
50. Fixtures for testing and troubleshooting circuitry, measuring transducersand product testing.
51. Fixtures ranging from engineering testing, incoming inspection,part qualifications and production.
52. Specific problem solving fixtures. Example: Troubleshooting audiblenoise, hands-free loopback.
53. Wide range of fixture applications, from high altitude to underwater,freezing to hot weather, high level electromagnetic noise field to ultralow level audio signals and more.
Calculations
54. Translate your product requirement into transducer specifications.
55. Check circuitry compatibility with audio transducers you selected.
56. Evaluate product end to end level and frequency response distribution.
57. Compare and evaluate audio specifications written in differentformats.
Simulations
58. Simulate end to end system for level, response, noise and distortiondistribution.
59. Create transducers models for accurate simulation of real likeconditions.
60. Simulate specific problem and specific solution.
61. Simulation files for circuit simulator of your choice.
Electronic Circuit Design
62. Translate product specification into circuitry requirement.
63. Create circuit requirement to match audio transducers.
64. Create requirement for power supply and pc board: Space neededand design rules.
65. Simulate, analyze and modify existing circuitry, predict and solveperformance problems.
66. Troubleshoot circuitry and propose available solutions, modificationsto meet requirement.
67. Find available on market replacement parts to make your productwork best.
Transducers Selection
68. Find audio components for your application and deal with transducers?vendors.
69. Design and build transducers test fixtures for microphone, speaker,receiver, buzzer, and ringer.
70. Evaluate your audio components per manufacturer or/and your productrequirement.
71. Evaluate how your audio components stand against another choices.
72. Prepare transducers replacement list.
73. Perform components qualification testing.
74. Select ? Tolerance? 揗ax Level?and 揗in Level?transducers forreference prototypes.
75. Evaluate transducers?compatibility with mechanical and electricaldesign, per product specification.
76. Analyze mechanics, transducers and electronics level tolerancebuild up.
77. Analyze mechanics, transducers and electronics frequency responsebuild up.
78. Perform microphones?RF susceptibility testing.
Dummy Prototype - product with audio transducers, no electronics
79. Create ? Tolerance? "Max Level?and 揗in Level?prototypes.
80. Evaluate how prototypes stand against product audio specification.
81. Perform preliminary Echo Return Loss test for all prototypes.
82. Assist with pc board layout design.
Functioning Prototype ?product with audio transducers and electronics
83. Create ? Tolerance? 揗ax Level?and 揗in Level?prototypes.
84. Evaluate how prototypes stand against product audio specification.
85. Evaluate pc board design in the audio and transducers areas.
86. Perform preliminary Echo Return Loss and Side Tone tests for allprototypes.
87. Perform prototypes?RF susceptibility testing.
88. Evaluate prototypes?voice quality with various scenarios. 
89. Perform Design Verification Testing. Perform System VerificationTesting.
90. Assist with pc board layout changes.
Production
91. Select audio transducers for production audio fixtures.
92. Design and build production audio test fixtures.
93. Evaluate and calibrate audio fixtures connected to production testerswith ? Tolerance? 揗ax Level?and 揗in Level?functioning prototypes.
94. Create level and frequency response limits envelopes for productiontesters with audio fixtures.
95. Measure 3 production units in audio lab (3 items) and on 3 productiontesters (9 items total). Confirm testers?repetition. Calibrate testers?limits envelopes.
96. Evaluate production testers?environment, including ambient noiseand RF field.
97. Perform production testers?and production audio fixtures?RF susceptibility.
98. Evaluate testers?results in mass production to ensure proper yield.Relax testers?envelope if justified.
99. Troubleshoot your product and fixtures to improve manufacturability.
Selected Topics
100. Implement Push To Talk PTT feature into your product..
101. Implement Hearing Aid Compatibility HAC into your product.
102. Implement Noise Canceling Microphone or Directional Microphone into your product.
103. Implement Micro Speaker into limited space around your mechanical design.
104. Reduce Audible Noise in your product.
105. Reduce Echo - improve echo return loss in your product.
Audio Seminar  Questions
1.    AC coupling capacitors: Coupling frequency corner per design'sfrequency corner. Differential input coupling.
2.    AC coupling capacitors tolerance and final CMRR. How 80dB CMRR turns into below 30 dB.
3.    Why test results may not fit tolerance mask, yet tested objectis fine.
4.    Tolerance mask: Do you specify Fixed Mask or Floating Mask?Mask types.
5.    Why tolerance masks for production tester and productspecification are different.
6.    Why sine sweep belongs to the past in the audio testing area- level and noise dependent response, level dependent noise floor, a lotof  DSP, steady tone seen as noise or whistle signal to mute. Whensine sweep is the best way to go.
7.    Why today high end audio analyzers may not tell the truth(calibration, repetition, side effects, test signal does not fit specificscenario).
8.    B&K? Audio Precision? ...? Which analyzer is best for you?Why?
9.    B&K? ? ...?  Which reference microphones are best foryou? Why?
10.  Why would I spend hundred dollars for microphone calibrationwhen my microphone works fine?
11.  B&K sound meter? Why? Which sound meter is right for you? Whatis type 1 and type 2?
12.  Sound meters design flaws their manufactures do not want you toknow.
13.  Why ringer sound testing with high end sound meter can be a verybad mistake.
14.  Do you properly select audio transducers for your application?Microphone? Receiver? Buzzer? Ringer? Speaker? Why your transducer maynot be selected properly while it works OK in your product?
15.  How do you select noise canceling microphone for your application?Common mistakes in microphone selection and noise cancellation estimate.
16.  What really is that 搉oise canceling effect? End to end componentsof acoustical noise cancellation, electrical noise cancellation, simulations.
17.  Test techniques for noise canceling microphone: Level, frequencyresponse, directionality, cancellation effect.
18.  How do you test your product with noise canceling microphone? Manyspeakers around? Frequency response at 0 deg & at 1"/2' or polarpattern? Best test strategy for your application.
19. Can your microphone cancel noise up to average 15 dB? Explaining mythabout 揳verage 15 dB noise canceling effect?
20.  Why each test technique brings different results and how tocompare such different results.
21.  When  揳verage?can substitute 搉ominal?for audio transducers?Common misconceptions.
22.  Do you have realistic expectation for audio transducer testingfor production troubleshooting?
23.  Why software can adjust microphone nominal level only in some cases?
24.  How you can change transducer level when no access to circuitryavailable.
25.  Why generic test fixture will not allow checking your audio partspecification accurately.
26.  Environmental concern ?can you buy microphone for 90 deg C storageand 65 deg C operation?
27.  Why should you care about weatherproof screen for audio transducers.
28.  Weatherproof or Waterproof? Are your audio transducers meetingfirst or second requirement?
29.  Can weatherproof screen change frequency response or acousticalecho for your product?
30.  Ringer's volume control. Ringer playing tunes. How do you turnvolume down?
31.  My ringer is too quiet and I have 1 week left. Can extension tubesolve my problem?
32.  Micropower operational amplifiers for audio ?mistakes with insufficientslew rate (Band, CMRR).
33.  Why engineering prototypes meet requirement yet production yieldwill be poor.
34.  You confirmed good echo performance in hands-free mode and complaintsare coming. What do you do?
35.  Do you avoid audio transducers from vendors with unknown reputation?Do you have peace of mind when buying more expensive microphone?
36.  Is custom made coupler from manufacturer a must for receiver transducer testing?
37.  Does noise from Signal to Noise Ratio (SNR) substitute noise fromNoise Floor measurement? When?
38.  Can I test ringer sound of 2 kHz with 5 kHz analyzer? Yes if?
39.  Techniques to control ringer output level and associated problems.
40.  When ringer meets requirement but only at 0 deg...
41.  Hard drive noise attenuating enclosure does not work as expected.Why?
42.  When and why 揂?filter is a must, test detail not present on manyspecifications.
43.  My  product does not meet requirement unless I turn off 揂?filter?
44.  What are A, B, C, G, U, AU filters?
45.  My cellular phone meets specification but does not sound right.What do I do?
46.  Why puff (not pop) effect may ruin performance of otherwise welldesigned microphone.
47.  How to test puff effect. Test fixture for good repetition.
48.  Specific cases when puff effect can be eliminated with high passfilter.
49.  Nature of puff effect. Can DSP fix poorly designed microphonehousing?
50.  Why side tone does not always indicate puff effect.
51.  When puff effect can degrade performance in hands free mode.
52.  Why 99% phones on market have puff effect and some are simple verybad.
53.  Which microphones exhibit best and worst puff effect and why.
54.  Puff effect and microphone directionality.
55.  Puff effect per weather proof screen in case when noise cancelingmicrophone has two ports.
56.  Directional microphone designed for small enclosures.
57.  Can cardioid microphone be made from noise canceling microphonecartridge?
58.  Can noise canceling microphone have rear port more sensitive thanfront port?
59.  How to modify Front to Rear port levels ratio with weather proofscreen.
60.  Weatherproof screen per frequency response and polar pattern. Canthey be entirely independent?
61.  Directional microphones with two cartridges. Advantages anddisadvantages. Design trade-offs.
62.  Can microphone cartridge be selected properly with no requirementprepared earlier?
63.  When microphone cartridge can be a source of customer complaintsafter production cranks zillions...
64.  Common mistake with ignoring microphone self noise and why.
65.  Can 6 mm condenser electret microphone match performance of 10 mmmicrophone?
65.  Can 6 mm condenser electret microphone work well for speechrecognition?
66.  Rare applications when 6 mm and 10 mm microphones work equallywell.
67.  Spring contacts or flex circuit? How do they compare frommicrophone performance stand point.
68.  Possible horror scenarios for spring contacts, flex circuit andsoldered wire connections.
69.  Can anyone solder microphone cartridges? Why not? Two horrorstories and how to avoid them.
70.  Microphone housing: Hard rubber? Soft rubber? How do you tellwhich one performs better?
71.  Maximum sound that condenser electret microphones can handle.Factors limiting high level signal.
72.  Which microphones accept high level best and worst. Can you definehighest sound level for your design?
73.  Can you influence microphone maximum level? Do you do it withoutknowing?
74.  Condenser electret microphone load. What is behind supply voltage range and load impedance.
75.  Can I use active load for condenser electret microphone? Caseswhen YES applies.
76.  Bipolar transistor acting as simulated inductance for condenserelectret microphone load.
77.  Can microphone load be utilized as frequency response network?Trade-offs and dangers here.
78.  Differential input connected to electret microphone cartridge.Common misconceptions.
79.  What is memory effect for electret condenser microphone cartridge?How to improve production yield for level testing.
80.  Are condenser electret microphone electrostatic sensitive, whenSource - Drain contacts have 1 kOhm connection? Why are microphones recommendedto handle with static protection?
81.  If static damages microphone cartridges, why are they shippedwithout proper electrostatic protection?
82.  Can soldering iron without static protection damage microphonecartridge?
83.  How soldering operation can ruin level tolerance build-upcalculations.
84.  Full list of level tolerances for every microphone project, from microphone housing to amplifier output.
85.  Can level tolerance build-up calculations substitute frequencyresponse tolerance build-up?
86.  Can frequency response for specific microphone element changebecause of microphone handling in production?
87.  Speakerphone acoustical testing scenarios and best referencemicrophones for each scenario.
88.  Test setup for speakerphone acoustical testing.
89.  Evolution of test signal for speakerphone testing. How do youdesign test signal for finding speakerphone side effects?
90.  Can voice quality be assessed properly with ONE working prototype?When?
91.  What factors to include when assessing voice quality for your product.
92.  Is voice quality fixed for your product or is it varying with time?How to check, predict.
93.  How to find voice quality problem source & differentiate voicequality between entire system per your product, product per audio transducers.
94.  How poor echo or side tone can make voice quality worse.
95.  Is voice quality fixed for your product or is it varying with time?How to check, predict.
96.  How do you determine Bluetooth protection level on Receive path?
97.  Can Bluetooth audio gain distribution be different between products?
98.  How do you measure Bluetooth loudness rating on Receive and Transmitpath?
99.  Can you use pink noise for Bluetooth audio measurements?
100.  Should you be concerned about handset echo when working on Bluetoothaudio compatibility?
101.  How do you prepare voice quality test setup for Bluetooth audio?
102.  Should you expect updated, completed Bluetooth audio specificationscoming soon?
103.  How long it takes to implement Hearing Aid Compatibility - HAC into your product?
104.  How do you check if your product is Hearing Aid Compatible - HAC?
105.  Where to start when implementing Hearing Aid Compatibility HAC.
106.  Should you be concerned about handset side tone (sidetone) when working on Hearing Aid Compatibility - HAC?
107.  The difference between meeting Hearing Aid Compatibility - HAC and fully meeting Hearing Aid Compatibility - HAC.
108.  How to resolve challenges with interpretation of Hearing Aid Compatibility Standard - HAC Standard.
109.  How to resolve challenges around equalization for various measurements for Hearing Aid Compatibility - HAC.
110.  Can different probes be used for various measurements related to Hearing Aid Compatibility - HAC?
111.  How to calibrate Hearing Aid Compatibility - HAC probes.
112.  Can Radial and Axial HAC probes be used at a time? Can they affect each other?
113.  Can presence of HAC probes affect magnetic field? Can it be compensated? Would such compensation always work?
114.  Hearing Aid Compatibility - HAC compliance per various software settings across entire volume control range.
115.  How to calibrate Hearing Aid Compatibility - HAC probes.
116.  Build your probes for Hearing Aid Compatibility - HAC or purchase them?
117.  Accuracy of various Hearing Aid Compatibility - HAC measurements.
118.  How to resolve component tolerances against requirements for Hearing Aid Compatibility - HAC.
119.  How to resolve temperature changes around HAC coil.
120.  What products may require Hearing Aid Compatibility - HAC, presently and in the future.
121.  Health issues around magnetic field associated with audio path of Hearing Aid Compatibility - HAC.
122.  How to resolve power consumption issues in Hearing Aid Compatibility - HAC design.
123.  Hearing Aid Compatibility design with Bluetooth.
124.  Axial and Radial components of Hearing Aid Compatibility - HAC.
125.  Can audio and RF portions of Hearing Aid Compatibility - HAC be met at different spots and still meet overall requirement?
126.  Fulfilling Hearing Aid Compatibility - HAC - listening test per specification. Practical valuation criteria and required measurements.
127.  Differences between passive and active probes for Hearing Aid Compatibility - HAC measurements.
128.  Where active probes shine and where passive probes are a must.

What you need is not listed here?   Write to Peter Sobczak at petersob@audioscientific.com.
Cellular Phone  - Performance Evaluation, test results shown in tableformat.

51vv社区视频在线视频观看


Cellular Phone - Side Tone Test, plots shown with side tone weightingapplied.

51vv社区视频在线视频观看


Cellular Phone - Receiver Frequency Response Test, plots shown before andafter circuit redesigned.


Cellular Phone - Echo Return Loss Test, plots shown with ERL weightingapplied.


Condenser Electret Microphone Cartridges, Self Noise Comparison Test - 3different models & vendors

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