Audio  Scientific             Audio   Expertise   for   Digital   World
 Telecommunications, Digital and Wireless engineers often add voice 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 in audio for telecom, wireless, digital, medical and hand portable products. We cover Bluetooth, 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),   Prior Accomplishments (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 Peter Sobczak, Audio Principal Engineer at   Audio Scientific, 11463 Tree Hollow Lane, San Diego, CA 92128.
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Acoustics Animations Sound Interactive Demos      Audio Test Equipment Manufacturers & Sources

Acoustical Anechoic Chambers    Auto Calculators & References    Audio Measurement Techniques  

Audio Compression       Acoustical Treatment Materials       Audio Marketplace         Audio Software 

Batteries    Bioacoustics - Ultrasound - Underwater - Wildlife     Bluetooth Audio  
Circuit Simulators

Class D Amplifiers             Data Loggers              Engineering Resources             EMF - Electrosmog

Electronic Circuits - Schematics & Tutorials             Interesting Sound Websites            Microphones

Microphone Cables                Noise             Noise Canceling Headphones & Active Hearing Protectors 

Noise Reduction & Intelligibility & Voice Quality & Speech Recognition      Ultra High End Devices

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

Ultra Low Noise      Ultra Low Power       Ultra Low Resistance       Ultra Fast Devices    
USB Audio

Room Acoustics           Sound Cards          Sound Meters           Special Audio Companies & Products

 Speakers          Transducers & Headsets & Suppliers           Wireless Audio &  Telecommunications
Engineering Service Examples
Provide access to our San Diego located sound anechoic chamber. Lease terms available.
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
Test Fixtures
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 working on your problem. Our mobile test setup allows automotive tasks like hands-free, speech recognition, echo canceller, echo return loss, audible noise and 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 monitor and car interior.
5. All steps from concept to production: Parts selection, documentation, schematics, drawings, procedures, testing, fixtures, prototypes and calibration references.
6. Analyze your needs and prepare custom tailored seminar for your crew.
7. General audio, analog circuitry, audio transducers, equipment or client 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 producing sound, devices and tricks involved.
11. Problem solving skills at expert depth available on “question and answer?basis.
12. Audio design, circuitry, transducers, parts selection, testing, troubleshooting, measurement, signal references, sound calibration, test signals, 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 and for specific application.
Design Review
16. Review requirements and prepare detailed list of audio design steps from concept to production.
17. Evaluate design progress and propose steps needed to speed it up and move it in right direction.
18. Compare yours and your competitor products in performance and specification terms.
19. Analyze your problem, find what you need and propose detailed action list.
20. Review schematics, mechanical drawings and audio components?specifications.
21. Review environmental requirement for your product and audio components.
22. Confirm “hearing aid compatibility? “voice recognition compatibility? “waterproof?and  “weatherproof?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 for each functioning block in the chain.
26. Specify or evaluate existing circuit interface compatibility with end devices like speaker, microphone.
27. Create simulation and build devices like loopback fixture, time delay fixture and more.
28. Digital - Analog - Sound - Microphone & Speaker conversion calculations.
29. Specify, select and incorporate semiconductors to meet specific goal.
30. Evaluate, test, troubleshoot and calibrate any portion or entire existing design, end to end.
31. Extract audio requirement from your documents, industry standards and customer needs.
32. Create requirement and buying list for requirement for engineering test equipment with fixtures.
33. Create requirement and buying list for production audio test equipment and production audio fixtures.
34. Create audio requirement and test procedure for production audio fixtures.
35. Create audio requirement and test procedure for production audio fixtures?transducers.
36. Create audio requirement and test procedure for product design verification.
37. Create audio requirement and test procedure for product system verification.
38. Create level and frequency response limits envelopes, for design and system verification testing.
Testing and recording
39. Measure and record everything that carries sound or audible frequency signal.
40. Measure and compare yours and your competitor product, specific segment 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, production troubleshooting, engineering prototypes, vendor samples and more.
44. Sound exposure, correcting test results for noise involved, various filters and custom-made test signals.
45. Wide range of setup scenario, anechoic chamber to hands-free, from moving 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, transducers selection, documentation.
50. Fixtures for testing and troubleshooting circuitry, measuring transducers and product testing.
51. Fixtures ranging from engineering testing, incoming inspection, part qualifications and production.
52. Specific problem solving fixtures. Example: Troubleshooting audible noise, hands-free loopback.
53. Wide range of fixture applications, from high altitude to underwater, freezing to hot weather, high level electromagnetic noise field to ultra low level audio signals and more.
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 different formats.
58. Simulate end to end system for level, response, noise and distortion distribution.
59. Create transducers models for accurate simulation of real like conditions.
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 needed and design rules.
65. Simulate, analyze and modify existing circuitry, predict and solve performance problems.
66. Troubleshoot circuitry and propose available solutions, modifications to meet requirement.
67. Find available on market replacement parts to make your product work 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 product requirement.
71. Evaluate how your audio components stand against another choices.
72. Prepare transducers replacement list.
73. Perform components qualification testing.
74. Select ? Tolerance? “Max Level?and “Min Level?transducers for reference prototypes.
75. Evaluate transducers?compatibility with mechanical and electrical design, per product specification.
76. Analyze mechanics, transducers and electronics level tolerance build up.
77. Analyze mechanics, transducers and electronics frequency response build up.
78. Perform microphones?RF susceptibility testing.
Dummy Prototype - product with audio transducers, no electronics
79. Create ? Tolerance? "Max Level?and “Min 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? “Max Level?and “Min 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 all prototypes.
87. Perform prototypes?RF susceptibility testing.
88. Evaluate prototypes?voice quality with various scenarios. 
89. Perform Design Verification Testing. Perform System Verification Testing.
90. Assist with pc board layout changes.
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 testers with ? Tolerance? “Max Level?and “Min Level?functioning prototypes.
94. Create level and frequency response limits envelopes for production testers with audio fixtures.
95. Measure 3 production units in audio lab (3 items) and on 3 production testers (9 items total). Confirm testers?repetition. Calibrate testers? limits envelopes.
96. Evaluate production testers?environment, including ambient noise and 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's frequency corner. Differential input coupling.
2.    AC coupling capacitors tolerance and final CMRR. How 80 dB CMRR turns into below 30 dB.
3.    Why test results may not fit tolerance mask, yet tested object is fine.
4.    Tolerance mask: Do you specify Fixed Mask or Floating Mask? Mask types.
5.    Why tolerance masks for production tester and product specification 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 lot of  DSP, steady tone seen as noise or whistle signal to mute. When sine 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 specific scenario).
8.    B&K? Audio Precision? ...? Which analyzer is best for you? Why?
9.    B&K? ? ...?  Which reference microphones are best for you? Why?
10.  Why would I spend hundred dollars for microphone calibration when my microphone works fine?
11.  B&K sound meter? Why? Which sound meter is right for you? What is type 1 and type 2?
12.  Sound meters design flaws their manufactures do not want you to know.
13.  Why ringer sound testing with high end sound meter can be a very bad mistake.
14.  Do you properly select audio transducers for your application? Microphone? Receiver? Buzzer? Ringer? Speaker? Why your transducer may not 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 “noise canceling effect? End to end components of acoustical noise cancellation, electrical noise cancellation, simulations.
17.  Test techniques for noise canceling microphone: Level, frequency response, directionality, cancellation effect.
18.  How do you test your product with noise canceling microphone? Many speakers around? Frequency response at 0 deg & at 1"/2' or polar pattern? Best test strategy for your application.
19. Can your microphone cancel noise up to average 15 dB? Explaining myth about “average 15 dB noise canceling effect?
20.  Why each test technique brings different results and how to compare such different results.
21.  When  “average?can substitute “nominal?for audio transducers? Common misconceptions.
22.  Do you have realistic expectation for audio transducer testing for 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 circuitry available.
25.  Why generic test fixture will not allow checking your audio part specification accurately.
26.  Environmental concern ?can you buy microphone for 90 deg C storage and 65 deg C operation?
27.  Why should you care about weatherproof screen for audio transducers.
28.  Weatherproof or Waterproof? Are your audio transducers meeting first or second requirement?
29.  Can weatherproof screen change frequency response or acoustical echo for your product?
30.  Ringer's volume control. Ringer playing tunes. How do you turn volume down?
31.  My ringer is too quiet and I have 1 week left. Can extension tube solve my problem?
32.  Micropower operational amplifiers for audio ?mistakes with insufficient slew rate (Band, CMRR).
33.  Why engineering prototypes meet requirement yet production yield will be poor.
34.  You confirmed good echo performance in hands-free mode and complaints are 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 from Noise 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 “A?filter is a must, test detail not present on many specifications.
43.  My  product does not meet requirement unless I turn off “A? 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 well designed microphone.
47.  How to test puff effect. Test fixture for good repetition.
48.  Specific cases when puff effect can be eliminated with high pass filter.
49.  Nature of puff effect. Can DSP fix poorly designed microphone housing?
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 very bad.
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 canceling microphone has two ports.
56.  Directional microphone designed for small enclosures.
57.  Can cardioid microphone be made from noise canceling microphone cartridge?
58.  Can noise canceling microphone have rear port more sensitive than front port?
59.  How to modify Front to Rear port levels ratio with weather proof screen.
60.  Weatherproof screen per frequency response and polar pattern. Can they be entirely independent?
61.  Directional microphones with two cartridges. Advantages and disadvantages. Design trade-offs.
62.  Can microphone cartridge be selected properly with no requirement prepared earlier?
63.  When microphone cartridge can be a source of customer complaints after production cranks zillions...
64.  Common mistake with ignoring microphone self noise and why.
65.  Can 6 mm condenser electret microphone match performance of 10 mm microphone?
65.  Can 6 mm condenser electret microphone work well for speech recognition?
66.  Rare applications when 6 mm and 10 mm microphones work equally well.
67.  Spring contacts or flex circuit? How do they compare from microphone performance stand point.
68.  Possible horror scenarios for spring contacts, flex circuit and soldered wire connections.
69.  Can anyone solder microphone cartridges? Why not? Two horror stories and how to avoid them.
70.  Microphone housing: Hard rubber? Soft rubber? How do you tell which 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 define highest sound level for your design?
73.  Can you influence microphone maximum level? Do you do it without knowing?
74.  Condenser electret microphone load. What is behind supply voltage range and load impedance.
75.  Can I use active load for condenser electret microphone? Cases when YES applies.
76.  Bipolar transistor acting as simulated inductance for condenser electret 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, when Source - Drain contacts have 1 kOhm connection? Why are microphones recommended to handle with static protection?
81.  If static damages microphone cartridges, why are they shipped without proper electrostatic protection?
82.  Can soldering iron without static protection damage microphone cartridge?
83.  How soldering operation can ruin level tolerance build-up calculations.
84.  Full list of level tolerances for every microphone project,  from microphone housing to amplifier output.
85.  Can level tolerance build-up calculations substitute frequency response tolerance build-up?
86.  Can frequency response for specific microphone element change because of microphone handling in production?
87.  Speakerphone acoustical testing scenarios and best reference microphones for each scenario.
88.  Test setup for speakerphone acoustical testing.
89.  Evolution of test signal for speakerphone testing. How do you design 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 voice quality 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 Transmit path?
99.  Can you use pink noise for Bluetooth audio measurements?
100.  Should you be concerned about handset echo when working on Bluetooth audio compatibility?
101.  How do you prepare voice quality test setup for Bluetooth audio?
102.  Should you expect updated, completed Bluetooth audio specifications coming 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
Cellular Phone  - Performance Evaluation, test results shown in table format.

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

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

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

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