100 Things #97: Zwicker Loudness Measurement

Zwicker Loudness Measurement, an indication of overall perceived loudness level, is calculated in SoundCheck using the Zwicker Loudness post processing step. Instead of just measuring the absolute sound pressure level in dB SPL relative to 20uPa, the Zwicker Loudness algorithm takes into account how humans hear sound level using  the PEAQ international standard. This is an ITU-developed standardized algorithm for objectively measuring perceived audio quality as subjects would in a listening test.

Zwicker Loudness Measurement

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Read more about more measurement features in SoundCheck.

More information is also available in the  SoundCheck Manual.


Video Script: Zwicker Loudness Measurement

Did you know that SoundCheck can calculate the overall perceived loudness level using a Zwicker Loudness post processing step ? Instead of just measuring the absolute sound pressure level in dB SPL relative to 20uPa, the Zwicker Loudness algorithm takes into account how humans hear sound level using  the PEAQ international standard. This is an ITU-developed standardized algorithm for objectively measuring perceived audio quality as subjects would in a listening test.

The input to this post processing step must be a spectrum of a complex signal in pascals or dBSPL. We can easily capture this in SoundCheck using an FFT or RTA broadband measurement using a calibrated Reference Mic signal path. To simulate the non-linearity of the ear, the Zwicker Loudness algorithm then filters these frequencies into auditory bands according to the bark scale – a frequency scale where equal distances correspond with perception. Once the spectrum is plotted on a bark scale, a frequency weighting is applied that correlates to human hearing. Finally, a level compression is applied and the loudness is output in Phons and Sones. The loudness spectrum can optionally be shown with the X axis either in Hertz or Bark.

Knowing the actual perceived loudness of a signal is extremely important for certain applications. For example, listeners that are trying to subjectively compare different headphones will be biased towards the louder one. If I want users to subjectively compare two different headphones, I need to make sure they are played back at the same level to avoid this bias. Looking at the 1kHz sensitivity of each headphone doesn’t take into account the difference in frequency response across the two devices. Often A-weighting is used to correlate measurements to human hearing, but a simple A-weighting curve makes a lot of assumptions such as what level of playback that will be used. Zwicker Loudness gives us a much more accurate perceived loudness, and enables us to precisely match the loudness, in phons, between the two devices regardless of level..

Zwicker Loudness is also widely used in communication testing for measuring loudness of both speech transmission, and ringtones. Check out our website to learn more.


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

Watch more

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.

100 Things #73: Active Speech Level Control in SoundCheck

SoundCheck’s incorporation of active speech level allows for stimulus to conform with telephony testing standards. This means testing to IEEE and TIA standards can be automated within a sequence, allowing an entire test to be run without operator intervention. Active speech level is incorporated directly into SoundCheck’s stimulus step, and becomes available when selecting dB RMS. Active speech level can also be used for setting voice activation levels or wake word testing for smart devices.

Active Speech Level Control in SoundCheck

Learn more about active speech level in SoundCheck

Our Telephones application page details all of the benefits of using SoundCheck to test your communications devices.

Video Script:

Did you know that SoundCheck offers Active Speech level control in both the stimulus editor and post-processing?

Many telephony standards such as IEEE and TIA specify speech stimulus levels in terms of active speech level, or ASL.  It can also be used for setting voice activation levels or wake word testing for smart devices.

When active speech level is used, signal levels are scaled using only the parts of the waveform where speech is actually present, rather than the overall RMS level. Silent gaps are excluded but utterances that are part of normal speech are included. This removes variability due to different speaking speeds and content when making measurements, and provides better consistency for standardized measurements.

Configuring ASL in SoundCheck is easy. Let’s take a look.

If you’re testing with speech, you’ll be loading a speech file as a WAV file stimulus. Simply select the file, or open it from the memory list. In the level drop-down, select dB RMS and this will enable the ASL checkbox. Make sure the ASL checkbox is selected, and set the level of your stimulus. 

ASL is also available as a post-processing step. Here, you have some additional parameters. You can adjust the Time Constant  – that’s the time constant of the exponential averaging used to measure the level of active speech . You can modify the Hangover Time – that’s the allowable time for silence between utterances, 200ms is the default. And you can also set the Margin  – that’s the  difference between threshold of activity and the active speech level. This is useful because if the background noise is high, you can reduce the margin to exclude the noise. 

When you are using Active speech level in post-processing, The ASL value in the Memory List displays the Percentage of time during the waveform where speech is active, the mean power of speech measured over the aggregate time of activity and the mean power of the waveform measured over its entire duration.

Active Speech Level is an optional module, and can be added to any SoundCheck system.

100 Things #53: Make ITU-T-P.63 Compliant POLQA Measurements With SoundCheck

Opticom’s POLQA algorithm is available as an option in SoundCheck, where it can be used in a test sequence to automate measurements, or for stand-alone analysis. POLQA is an alternative to a panel of human listeners for quantifiable measurement of speech degradation.

POLQA Analysis within SoundCheck

Learn more about POLQA Analysis Using SoundCheck

Read about POLQA for SoundCheck, or check out our more detailed video demonstrating POLQA measurements.


Video Script: Make ITU-T-P.63 Compliant POLQA Measurements With SoundCheck

Did you know that Opticom’s POLQA algorithm is now integrated into SoundCheck? You can access all the functionality of this algorithm through the familiar SoundCheck interface, and it can be integrated into test sequences for rapid, automated measurement.

POLQA Analysis is a fast and cost-effective alternative to a panel of human listeners for perceptual measurements of speech degradation in communications applications. It compares a reference and response waveform and returns a mean opinion score, or MOS, on a scale of 1 to 5.

This SoundCheck add-on module operates just like any other post-processing step. You configure the reference and response waveforms, set test parameters, and define outputs through the familiar soundcheck interface, and SoundCheck returns results as graphs and tables like any other analysis. It can naturally be used within sequences to accelerate and simplify test procedures, and can also be used to process imported data using Batch File Processing. This means that you can quickly calculate scores for hundreds or even thousands of waveforms captured offline, as well as those that you have measured in SoundCheck.

SoundCheck uses Version 3 of the algorithm which implements the ITU-T P.863 standard, but it also includes the option to analyze data using the older Version 2.4 for correlation with measurements made on older systems.

This algorithm is applicable to many communications devices from traditional phones to smart devices. For example, you can assess the impact of a noise reduction algorithm on an audio communication system, evaluate the perceived audio degradation in a Bluetooth connection due to packet loss, or quantify the impact of various speech codecs on perceived speech quality.

If you want to learn more, check out our YouTube channel for a more complete demonstration of this capability.






Communications Testing Seminar

Communications tests are not just for telephones! In this demo-packed seminar with communications industry expert, John Bareham, we demonstrate how to evaluate devices such as smart speakers, headphones and wearables as well as all types of phones using industry standard procedures. We discuss equipment, standards, and demonstrate sections of the TIA920B and TIA5050 standards, as well as Doubletalk measurements and POLQA analysis, all within SoundCheck.


Communications testing demonstrations include:

  • TIA-920B
  • TIA-5050
  • Doubletalk

Presenters: Steve Temme, John Bareham, Les Quindipan
Duration: 52 mins

Communications Testing Measurement Resources

This seminar was originally broadcast on Dec 14th 2022. The recording below does not include the live Q&A at the end for attendee confidentiality reasons. However, several links to additional resources were provided during the Q&A session, and these are provided below.

  1. More about the TIA-920 Test sequence for SoundCheck This for-purchase sequence measures communications devices to TIA-920-B
  2. More about the TIA-5050 Test sequence for SoundCheck This for-purchase sequence measures communications devices to TIA-5050
  3. More about SoundCheck’s implementation of the POLQA Algorithm.

More about how to Measure Communications Devices

Check out our main page on Communications Testing, which includes links to test sequences, relevant products and more for testing telephones and other communications devices.

TIA – the Telecommunications Industry Association. Listen, Inc. works closely with this group to ensure that our measurement capabilities align with the measurements recommended by the AES.