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Frequency Normalized Distortion Seminar

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Recent transducer development, particularly piezo-MEMS loudspeakers, have brought renewed attention to Normalized Distortion (also known as Frequency Normalized Distortion), because it is essential to accurately characterize their behavior.

Normalized Distortion is a measurement algorithm first proposed in a 1993 AES paper by Listen president Steve Temme during his time at Brüel & Kjær. Although it has been available in SoundCheck since 1996 and used by some engineers for nearly 30 years, interest in the technique has surged recently. This renewed focus is driven both by the industry’s increasing emphasis on correlating measurements with audibility – an area Listen has long prioritized – and by the emergence of new microspeaker technologies that cannot be fully evaluated using conventional distortion measurements.

In this seminar, we’ll first explain distortion mechanisms and talk about correlating measured results to what we hear using masking curves. We’ll then examine how normalized distortion differs from the conventional approach and show why it’s essential for characterizing modern piezo-MEMS loudspeakers.

This seminar presentation includes:

  • Psychoacoustics
  • Even Order Distortion
  • Odd Order Distortion
  • Threshold of Hearing
  • Auditory Tonal Masking
  • Masking vs. Level
  • Masking vs. Frequency
  • Masking of High Order Harmonics
  • Real-Time Masking Curves
  • Linear vs Nonlinear Effects
  • Plotting Harmonic Curves
  • Dynamic Speaker Normalized THD Measurements
  • Conventional Dynamic vs. MEMS Speaker
  • MEMS Speaker Measurement Test Configuration
  • Piezo-MEMS Speaker Conventional THD Measurements
  • Piezo-MEMS Speaker Normalized THD Measurements

Presenter: Steve Temme
Duration: 30 Mins

Frequency Normalized Distortion Resources

How to Graph Distortion Measurements: Original 1993 paper where normalized THD was introduced.

The Value of Normalized Distortion: Blog post on the value of normalized distortion.

MEMS Speaker Measurements: 100 Things video on MEMS speaker measurements.

Smart Glasses Audio Measurement: A video demo on how to measure smart glasses audio.

Production Line Audio Test Seminar

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End-of-line audio test is critical to ensure product quality. Good production line audio measurements involve identifying the correct measurements, carefully selecting equipment, and accurately configuring and optimizing tests. In this 45-minute long seminar, Steve Temme and Mark Latshaw share valuable tips and tricks to ensure a smooth transition from the R&D lab to large-scale manufacturing. Topics include: end-of-line measurements, test equipment, calibration, optimizing your measurements, setting limits, saving data, factory control, test specification and security and more.

Production line audio test topics include:

  • What to measure: the basic production line electroacoustic measurements and what they tell you
  • The equipment – the software, hardware, and test fixtures you’ll need to make audio measurements
  • Optimizing your test – limit setting, optimizing your test speed and resolution, ensuring accuracy and more
  • Integrating your audio test with the overall test environment – database integration, python control etc.
  • Test specification and security – ensuring that your tests are run exactly as you intended.

Presenters: Steve Temme, Mark Latshaw
Duration: 45 Mins

Production Line Audio Test Resources

This seminar was originally broadcast on September 17th 2024. The recording above 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. Transitioning Audio Tests from R&D to the Production Line An article originally published in the March 2023 issue of AudioXpress.
  2. End of Line Distortion Measurements An article originally published in the 2022 Loudspeaker Industry Sourcebook.
  3. Why Standardize on SoundCheck for Production Line Audio Test? Webpage highlighting the benefits of SoundCheck for production testing.
  4. SoundCheck for Production Line Audio Test Need the executive summary? Or need to convince a busy person to take a look at SoundCheck? This short video sums it all up in just 5 minutes.
  5. Using a barcode reader with SoundCheck A short video demonstrating use of a barcode scanner to input data into SoundCheck.

SoundCheck for End-of-Line Test

Check out our main SoundCheck page for more information.

 

Smart Device Testing Seminar

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Testing smart devices such as smart speakers, hearables, watches and more involves a combination of tests from many different application areas, ranging from simple transducer tests to open loop tests, Bluetooth measurements, voice activation tests, telecoms standards, hearing aid measurements and more. In this demo-focused seminar, we demonstrate how SoundCheck makes all the measurements you need throughout the entire smart device design process from component selection to pre-qualification testing.

Smart device testing demonstrations include:

  • Component tests: MEMS microphone measurement, directional microphone measurement, speaker evaluation
  • Prototype tests – open loop speaker test on a smart speaker, open loop microphone test on a smart speaker, Bluetooth hearables test, headphone Active Noise Cancellation (ANC) Measurement
  • Background Noise Tests: calibration, using pub noise to evaluate a microphone’s ability to reject background noise

Presenters: Steve Temme, Mark Latshaw, Steve Tatarunis
Duration: 48 Mins

Smart Device Measurement Resources

This seminar was originally broadcast on June 6th 2023. 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. Internally routing audio: Open Loop microphone testing requires audio to be routed into SoundCheck. We recommend:
    1. Virtual Audio Cable for Windows: https://vac.muzychenko.net/en/index.htm
    2. Soundflower for Mac: https://github.com/mattingalls/Soundflower
  2. In response to a question about whether haptic feedback could be measured in a smartwatch, we shared a SoundCheck test sequence for measuring haptic feedback: https://www.listeninc.com/products/test-sequences/free/linear-motor-test-sequence/
  3. We touched briefly on communications audio tests when smart speakers are used as hands-free devices. To learn more about Communications Testing techniques and standards, please see our Communications Testing Seminar.
  4. Similarly, in answer to a question about testing automotive infotainment systems, we shared our Automotive audio testing seminar

More about how to Measure Smart Devices

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

 

Communications Testing Seminar

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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
  • POLQA

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.

External Control of SoundCheck Seminar

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SoundCheck has led the way in production line audio measurement for over 25 years with its sophisticated suite of audio measurement algorithms that offer precise measurement, fast throughput, excellent noise immunity, and world-class reliability. However, many audio manufacturing factories are moving towards large, highly customized, integrated test configurations to evaluate products, not only for audio integrity, but often video, visual and other performance defects. This seminar explains how external control capability brings the advantages of SoundCheck into your automated test environment using any programming language compatible with TCP/IP  including C, C+, Python, LabVIEW and more.

External Control demonstrations include:

  • Enabling TCP-IP in SoundCheck, and an overview of commands
  • Using external control to open up and run a SoundCheck sequence using a python script, and returning data for use in any application
  • Changing test parameters via external control, so that test procedures can be simplified by adapting test conditions on the fly for different products
  • Loading, playing and controlling volume of  a test signal on a DUT  using a custom step in a SoundCheck sequence.
  • Using external control to automatically equalize wave files loaded into SoundCheck via TCP/IP
  • Using MATLAB with SoundCheck

Presenters: Mark Latshaw, Pranav Swaroop
Duration: 30 Mins

More about External Control of SoundCheck

The SoundCheck manual includes a full list of TCP/IP commands for use with SoundCheck, and an explanation of the JSON formatted return.

Learn more about SoundCheck for production test.

Resources for controlling SoundCheck with programs externally

To learn more about the Python programming language used in this seminar, check out the official Python website.

To learn more about MATLAB by MathWorks, check out the official MATLAB website.

Automotive Audio Measurements (Seminar): Frequency Response, Max SPL, Buzz, Squeak & Rattle

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In this practical online seminar, Steve Temme demonstrates in-car measurement of frequency response, Max SPL, and Buzz, Squeak and Rattle using a Bluetooth connection. He discusses considerations such as physical setup, infotainment system controls and the measurement parameters. We then discuss connectivity for automotive testing, explaining and demonstrating the various connectivity options including USB drive, Bluetooth and A2B bus. Finally, we take a look at some of the other audio measurements that you can make using SoundCheck, for example active noise cancellation and voice assistance readiness.

Automotive Audio testing demonstrations include:

  • Frequency Response
  • Max SPL and Max SPL Spectrum
  • Buzz, Squeak & Rattle
  • Connectivity Options – USB, Bluetooth, A2B bus
  • ANC and Voice assistance readiness

Presenters: Steve Temme
Duration: 32 Mins

Automotive Audio Measurement Resources

This seminar was originally broadcast on July 21st 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. Test sequence for in-car audio measurements. This sequence measures the impulsive distortion, frequency response, and maximum sound pressure level of a vehicle.
  2. An article by Steve Temme on automotive Max SPL measurements. Originally published in VoiceCoil magazine, June 2022.
  3. Read the full ISEAT paper, presented by Steve Temme at the 9th ISEAT Conference (2024) Shenzhen, China

More about how to Measure Automotive Audio

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

Learn more about Connecting to Automotive Infotainment Systems

Maximum SPL measurements in cars

Buzz, Squeak and Rattle measurements

AES Technical Committee on Automotive Audio. Listen, Inc. works closely with this group to ensure that our measurement capabilities align with the measurements recommended by the AES.

More about Standardized Automotive Audio Testing

Check out our latest seminar video where Steve Temme presents the current status of standardized automotive audio measurements. It covers key tests recommended by the AES Technical Committee on Automotive Audio, including frequency response, Max SPL, and impulsive distortion, with real in-car demos. It also explores extended measurements such as THD, IM distortion, and spectral uniformity to give a more complete picture of system performance.

Standardized Automotive Audio Testing Seminar

Virtual Instruments Seminar

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Virtual instruments, included in SoundCheck, are a cost-effective and portable software-based alternative to hardware instrumentation, ideal for making quick measurements or viewing device behavior in real time. In this educational seminar, Les Quindipan walks through a demonstration of the virtual instruments in SoundCheck, showing off some of their lesser-known capabilities. These include the signal generator, multimeter, oscilloscope/spectrum analyzer, real time analyzer, frequency counter and distortion analyzer. The strip chart recorder, which expands the capability of these instruments to record measurements over a period of time, are also discussed.

Virtual Instrument testing demonstrations include:

  • What are Virtual Instruments, and how to use them in SoundCheck
  • How instruments use existing SoundCheck signal paths and calibrations
  • Tour of individual instruments
  • Using multiple instruments and saving Virtual Instrument Configuration Files (or .vic files)
  • Explore using Virtual Instruments in a SoundCheck sequence
  • Practical applications of SoundCheck Virtual Instruments

Presenters: Les Quindipan
Duration: 30 Mins

Virtual Instrument measurement resources

Check out our main page on SoundCheck Features and Functionality for more detail on all of SoundCheck’s audio test and measurement capabilities.

The Virtual Instrument example sequence included in the SoundCheck installation is a great starting point for working with virtual instruments. The sequence automatically performs measurements with various virtual instrument configurations with operator message details about each configuration. This sequence can be used as a template sequence to build a custom test sequence.

More about testing with Virtual Instruments

The Multi-RTA virtual instrument in SoundCheck features true recursive digital filtering, and conforms to the ANSI S1.11-2004 standard.

Production Testing Seminar

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In this short seminar, Les Quindipan explores the use of SoundCheck for end-of-line electroacoustic production testing. He discusses typical test configurations and the type of measurements that can be made, how to set pass/fail limits and how to optimize tests for high throughput.

He also explains how SoundCheck is easily scaled for high volume electroacoustic testing, with such features as external control via another program and auto-saving data to databases, and how SoundCheck’s capabilities are easily expanded through the use of custom steps to control all types of devices and test fixtures.

This seminar will interest anyone considering a production line implementation of SoundCheck, or curious as to how to transition R&D measurements to fast and effective end-of-line test.

Production Testing demonstrations with SoundCheck include:

  • How to scale for high volume electroacoustic production testing, saving time and money
  • Typical audio measurements used in production testing
  • Production test setups
  • Optimizing test times and accuracy
  • Setting pass and fail limits in a test sequence
  • Auto-saving data
  • Custom Step Applications
  • Controlling SoundCheck externally from another program

Presenters: Les Quindipan
Duration: 18 Mins

More about Electroacoustic Production Testing with SoundCheck

A read on about at using SoundCheck for Production, as well as the transition of testing in a production environment from SoundCheck in the R&D Lab.

Take a closer look at the hardware used in this seminar, the AmpConnect 621.

Resources for Production Testing with SoundCheck

Learn more about the  WATS test data management system referenced in the video.

Basic Loudspeaker Testing Seminar

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This introductory seminar is aimed at anyone new to audio measurement, specifically loudspeaker testing. It begins with an introduction to the basic design of a loudspeaker, including how a typical loudspeaker works. Various loudspeaker measurements are explained, such as frequency response, distortion, sensitivity, phase/polarity and impedance, and how they might offer indications as to potential defects in a speaker. Typical test configurations for both R&D and end-of-line production test are shown. A complete speaker test is demonstrated, using SoundCheck and our free Loudspeaker complete test sequence. This includes setting up software and hardware, calibrating and configuring the test (e.g. setting pass/fail limits) and a discussion of the results.

Basic Loudspeaker Testing demonstrations include:

  • Anatomy of loudspeaker design
  • How a loudspeaker works
  • Loudspeaker test setup with SoundCheck
  • Considerations when testing a loudspeaker in an R&D versus production environment
  • Critical measurements like frequency response, sensitivity, phase, polarity, impedance, and distortion

Presenters: Les Quindipan
Duration: 22 Mins

Basic Loudspeaker Testing measurement resources

Complete End-of-Line Speaker Test: This free test sequence performs a full suite of basic measurements for a loudspeaker, featuring our two new perceptual distortion metrics. ePRB, or enhanced Perceptual Rub & Buzz is used to detect and differentiate audible distortion from total distortion. eLP, or enhanced Loose Particles, performs transient distortion measurements even in the presence of background noise.

More about Basic Loudspeaker Measurement

Johan Segeborn’s video “How Does A Speaker Work?” is an excellent reference for loudspeaker behavior.

Bluetooth Testing Seminar

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Les Quindipan of Listen, Inc. and Kristopher Hett of Portland Tool & Die demonstrate Bluetooth testing with a variety devices, test parameters, and testing considerations. Kris Hett introduces the Portland Tool & Die Bluetooth interfaces that are used to connect the device under test to the measurement system. He discusses the technical specifications, and explains the differences between these and other types of Bluetooth interfaces. Les Quindipan then demonstrates how these have been fully integrated into SoundCheck for simple plug and play operation, and how they can be used in test sequences. He also highlights some of the algorithms included in SoundCheck that overcome Bluetooth-induced time delays, thus enabling these devices to be tested in a similar way to their wired counterparts. A complete test on a Bluetooth speaker and a Bluetooth Headset is demonstrated.

Seminar demonstrations include:

  • Overview of Portland Tool & Die Bluetooth interfaces features and functionality
  • Portland Tool & Die software control integration with SoundCheck
  • SoundCheck configuration and calibration for testing Bluetooth devices
  • Software control of Portland Tool & Die devices within a SoundCheck sequence
  • Demonstrations of sequence measuring Bluetooth headsets and speakers

Presenters: Les Quindipan, Kristopher Hett
Duration: 30 Mins

Bluetooth testing Resources

  • Our sequence library contains many ready-to-run sequences for testing Bluetooth devices, available for download for no charge.

More about testing Bluetooth devices

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

ABOUT LISTEN INC

Listen is a global leader in audio measurement and analysis, with over 30 years’ experience developing innovative test methods and algorithms. SoundCheck, our powerful software-based audio analyzer, pairs with our test interfaces, precision microphones, and accessories to offer a complete solution for testing loudspeakers, headphones, microphones, smart devices, communication systems, hearing aids, automotive audio, and more. Trusted by engineers worldwide, Listen delivers the accuracy and flexibility essential for modern audio testing, from the R&D lab to the production line.

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