Tag Archive for: microphone

Microphone Polar Plot Substitution Method Using Outline ET250-3D

This sequence measures the directional response of a microphone and graphs the result as a polar plot. A log sweep stimulus is played from 100 Hz to 10 kHz at each angular increment, and the acquired waveform is analyzed using the Time Selective Response algorithm. This method allows the test to be performed in a non-anechoic environment by placing a window around the direct signal, eliminating the influence of reflections. Commands are sent automatically to the Outline ET250-3D turntable via an ethernet connection, instructing it to move in 10 degree increments after each measurement. The sequence measures the response every 10 degrees from 0 to 180 and mirrors the polar image, which simulates a full 360 degree polar and saves test time. The response at each angular increment is compared against the on-axis response to create a normalized curve. This removes the influence of the device’s frequency response and sensitivity, such that the polar plot only shows the directional response. The final display also contains a graph of the directivity index in decibels versus frequency.

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Microphone Acoustic Overload Point (AOP)

This sequence measures the acoustic overload point (AOP) of a microphone – the SPL required to produce 10% THD @ 1kHz from the microphone’s output.
A 1 kHz amplitude sweep from a calibrated source speaker is applied across a range from 120 dB SPL to 135 dB SPL.The recorded time waveform is then analyzed using the HarmonicTrak algorithm to produce a Fundamental and THD vs. Level curve. An intersection post processing function identifies where the THD curve intersects 10% and that level is is used in a limit step to produce a Pass/Fail AOP verdict.

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Advanced Microphone Measurements Part 2

Listen’s Support Manager, Steve Tatarunis, discusses some of the more advanced aspects of microphone measurements. This is an expansion of material covered in the Basic Microphone Testing webinar, and part two of the full advanced microphone measurements seminar. Advanced Microphone Test part 1 shows microphone measurements like polar plotting, open loop, active/passive noise rejection, and more. This seminar is of interest to anyone testing microphone characteristics, both in an R&D and production line environment. The tests featured in this seminar can be used both at component level, whether selecting microphones for devices or component QC, or these tests can be performed on finished products like smartphones, smart speakers, and more.

Seminar topics include:

More advanced aspects of microphone testing including:

  • Phase
  • Open loop microphone testing for voice activated devices such as smart speakers, automotive audio, etc.
  • Intermodulation distortion
  • Advanced hardware and test configurations for measuring microphone arrays
  • Beamforming with broadside and endfire arrays
  • Measuring MEMS devices frequency, sensitivity and power supply rejection (PSR) performance

Presenters: Steve Tatarunis
Duration: 40 Mins

Advanced microphone measurements resources

SoundCheck comes with many pre-written sequences including the sequences demonstrated in this seminar including the microphone test sequences for measuring microphone self noise, microphone substitution, frequency response and sensitivity, and open loop. Additionally, we offer the sequences featured in this seminar measuring digital MEMS microphones and microphone intermodulation distortion in our sequence library for download. Along with the sequences featured in this seminar, our sequence library is full of additional pre-written sequences for basic microphone measurement.

More about advanced microphone measurements

Check out our main page on Microphones, which includes links to test sequences, relevant products and more.

Advanced Microphone Test Part 1

Listen’s Support Manager, Steve Tatarunis, discusses some of the more advanced aspects of microphone test. This is an expansion of material covered in the Basic Microphone Testing webinar. This seminar is of interest to anyone testing microphone characteristics, both in an R&D and production line environment. This is part one of two in our advanced microphone measurement seminar series, with part two also available on our website. The tests featured in this seminar can be used both at component level, whether selecting microphones for devices or component QC, or these tests can be performed on finished products like smartphones, smart speakers, and more.

Seminar topics include:

  • Demo of microphone test methods substitution, equalized source, and transfer function in SoundCheck
    • How to calibrate for these measurements
    • What are the trade-offs?
  • Advanced microphone test measurements
    • Polar plot
    • Self noise and signal to noise
    • Open loop
    • Active/passive noise rejection

Presenters: Steve Tatarunis
Duration: 63 Mins

Advanced microphone test resources

SoundCheck comes with many pre-written sequences including the sequences demonstrated in this seminar including the microphone test sequences for measuring microphone self noise, microphone substitution, frequency response and sensitivity, and open loop. Additionally, we offer the sequences featured in this seminar microphone polar plot measurements with the new MDT-4000 turntable and open loop microphone test in our sequence library for download. Along with the sequences featured in this seminar, our sequence library is full of additional pre-written sequences for basic microphone measurement.

More about advanced microphone tests

Check out our main page on Microphones, which includes links to test sequences, relevant products and more.

Basic Microphone Measurement Seminar

Technical Support Manager, Steve Tatarunis discusses and demonstrates basic microphone measurement, and how to measure characteristics that matter. Three different basic microphone test methods are explained including substitution, equalized source, and two-channel transfer function. Testing microphones in SoundCheck yields a full array of important results, since SoundCheck can be used to test microphone specifications including frequency response, sensitivity, impedance, directivity/polar pattern, polarity, dynamic range, signal to noise/self-noise, polarization/bias. Finally, two basic microphone measurement techniques are demonstrated: equalized source, and microphone substitution.

 

Seminar topics include:

  • Common microphone types and how they work
  • Microphone specifications
  • How to measure microphones using the two standard methods available in SoundCheck
    • Substitution method
    • Equalized speaker method
  • R&D and production test environments
  • Important measurements such as frequency response, sensitivity, etc.

Presenters: Steve Tatarunis
Duration: 34 Mins

Basic microphone measurement resources

Our sequence library is full of pre-written sequences for basic microphone measurement. Additionally, SoundCheck comes with many pre-written sequences including the sequences demonstrated in this seminar. To take these sequences to the next level, we offer more complex testing scenarios like microphone polar plot measurements with the new MDT-4000 turntable.

More about basic microphone measurement

Check out our main page on Microphones, which includes links to test sequences, relevant products and more.

Microphone SNR Measurement (Background Noise Method)

This sequence characterizes a microphone’s ability to passively and/or actively reject noise in the user’s environment.  Unlike traditional microphone SNR measurements which calculate a ratio based upon a reference signal and the microphone’s noise floor, this method utilizes a signal (speech played from a mouth simulator) and noise (background noise played from two or more equalized source speakers) captured by both a reference microphone and the DUT microphone.

First a recording of the baseline ambient noise in the test environment is made and a 1/3 octave RTA spectrum is calculated from the recording. Next, the speech signal (mouth simulator) and noise signals (Left and Right speakers) are played consecutively and recorded separately using the reference microphone. A 1/3 octave RTA spectrum is calculated from each recorded time waveform. Next the same measurements are repeated using the DUT microphone. The resulting RTA spectra are then post processed to produce a signal gain spectrum and a noise gain spectrum which are then used to derive the SNR spectrum of the DUT mic. For best accuracy, the Signal and Noise spectra should be at least 5 dB above the ambient noise floor of the measurement environment.

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