Tag Archive for: test

100 Things #76: Using SoundCheck to Test Communications Devices

Modern devices let us communicate with each other more than ever, in new and exciting ways. Telecommunications devices have evolved, so have the methods to test them. Today’s communications standards test the functionality of devices connected via USB, Bluetooth, and the cloud. SoundCheck facilitates testing these devices with the ability to connect to multiple devices with different hardware connectivity. Configuring SoundCheck to run these often complex test sequences saves time, allowing the whole test to run without operator interruption.

Using SoundCheck to Test Communications Devices

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Our full Communications Testing seminar features Listen president Steve Temme and Communications Consultant John Bareham giving a deep dive on tests like Doubletalk, TIA-5050, POLQA, TIA-920B

Learn more about using SoundCheck for communications tests

Our main page on communications testing details the benefit of using SoundCheck for telecommunication tests, possible measurements, communications test configurations, and pre-written sequences testing to standards like TIA 920-B, ETSI ES 202 396-1, and more.

Video Script:

You know that SoundCheck measures acoustic parameters, but did you know that you can also implement industry-standard tests on a wide range of communications devices?

Speech communication always involves talking and listening. Today we frequently communicate using various consumer electronic devices such as headphones, hearables, smart glasses, watches, smart speakers, intercom systems, 2-way radios and, of course, smartphones. 

To accommodate this shift, industry-standard communications tests have evolved from tests on old-fashioned wired “telephones” to more sophisticated tests on these more complex devices. These devices also connect in different ways, including USB, Bluetooth, and the cloud. 

Although it’s often not required to test these devices to industry standards, it’s very worthwhile to make these measurements from a product performance perspective, especially if you anticipate needing to pass 3rd party verification.

With SoundCheck, you can measure voice quality performance to TIA, ETSI and other standards. It’s easy to test via direct connection, USB, or a Bluetooth interface. Seamless integration with your computer’s audio also makes it easy to route signals between the device, the cloud, and your computer for open loop measurements.

Several features recently introduced in SoundCheck facilitate more advanced communications tests, such as Active Speech level, RMS level versus time, silence stimulus step and histogram post-processing steps. These support measurement of Doubletalk, echo detection, background noise evaluation, and more. The optional  POLQA module also enables speech quality analysis using the POLQA algorithm directly within SoundCheck.

Standardized communications test sequences can be very complex, and SoundCheck contains all the functionality to create these tests. We also offer shortcuts with our pre-written test sequences for TIA-920-B, TIA-5050, and Doubletalk to ITU-T P.502 and ETSI TS 126132. These complex test sequences automatically implement entire tests according to the standards, saving considerable development time, and ensuring that measurements are made correctly.

All these tests are fully demonstrated. in Listen’s communications seminar – check it out to learn more.

In-Car Audio Measurements

Screenshot showing in-car audio measurement sequence final display showing frequency response, distortion and Max SPL

Final display of in-car audio measurement sequence showing frequency response, distortion and Max SPL

This in-car audio test sequence measures the transient distortion (also known as buzz, squeak, and rattle, Rub & Buzz, or impulsive distortion), frequency response, and maximum sound pressure level of a vehicle infotainment system to the methods outlined in the Audio Engineering Society Technical Committee on Automotive Audio (TC-AA) in-vehicle measurements draft white paper.  The three measurements are incorporated into one overall test sequence, making it fast and simple to run the entire suite of tests. This sequence facilitates evaluation of the committee’s proposals, and also serves as a basis for any similar in-house measurements. The white paper (linked above) outlines both measurement methods and physical configuration such as microphone and seat positioning in an effort to simplify comparison between vehicles. This test sequence may, of course, be used with your own in-house physical configuration if adherence to the TC-AA guidelines is not essential.

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Complete Test Sequence

The purpose of this sequence is to perform a full suite of basic measurements for a loudspeaker. A 500 mV stepped sine sweep from 20 kHz to 50 Hz is played through the speaker and measured via two channels of the audio interface. A calibrated reference microphone is connected to one of the channels, and an impedance reference is connected to the other.

A HarmonicTrak™ analysis step analyzes the recorded waveform from the reference microphone, and outputs frequency response, THD, Rub & Buzz, and various harmonic curves. A second analysis step analyzes the waveform from the impedance reference and outputs a curve of impedance versus frequency. A post processing step is used to estimate the characteristics of the impedance curve and calculates the max impedance, resonance frequency, and the Q of the resonance peak.

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Bluetooth Headset Test Sequence

The purpose of this sequence is to test a Bluetooth headset using a mixture of analog and digital channels. First, a Multitone stimulus is created with SoundCheck, played back over the Bluetooth headset (at 8 kHz) and recorded by a head and torso simulator’s ear (at 44.1 kHz). Then the same Multitone stimulus is played back through the head and torso’s mouth simulator (at 44.1 kHz) and recorded via the Bluetooth headset (at 8 kHz).

Due to inaccuracies of clock frequency, the Bluetooth device playback sampling rate is often slightly different than it is specified. Therefore, in SoundCheck, the Recorded Time Waveforms are frequency shifted to correct for the inaccurate sampling rate. The exact device playback sampling rate is displayed.

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Headphone Test Sequence

This headphone test sequence measures a stereo headphone. Both left and right earphones are measured simultaneously using a standard 1/12th Octave stepped-sine sweep from 20 Hz to 20 kHz.

The analysis is then performed using Listen’s HarmonicTrak™ algorithm that measures harmonic distortion and fundamental frequency response simultaneously. Then the diffuse-field and free-field corrected Fundamentals are calculated. The diffuse-field correction curve compensates for the overall frequency response from the diffuse-field (sound in every direction) to the eardrum and includes the effects of the head, torso, pinna, ear-canal and ear simulator. The free-field correction curve compensates for the overall frequency response from the free-field (sound at 0 degree incidence to the nose of the Head and Torso Simulator – HATS) to the eardrum.

Further post-processing of the signal compares left and right earphone responses to show the difference curve (magnitude and phase are available). The average sensitivity from 100 to 10 kHz for both left and right earphone is calculated and the total harmonic distortion displayed.

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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.