Frequency Normalized Distortion – A Necessity for Modern Transducers

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Normalized THD articleFrequency Normalized Distortion, or Normalized THD is a more accurate method for measuring distortion in transducers, and should be used alongside conventional THD measurements. Here’s the background from the creator of the original measurement.

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More about Frequency Normalized THD

This article examines the limitations of conventional Total Harmonic Distortion (THD) calculations when evaluating modern acoustic transducers. Conventional THD shifts harmonics and compares them to the fundamental at the stimulus frequency. This combines the device’s linear and non-linear distortion, often resulting in an overestimation of low-frequency distortion and an underestimation of high-frequency distortion due to normal passband roll-offs.

To accurately isolate true non-linear mechanisms, Frequency Normalized Distortion compares harmonics to the fundamental at their actual measured frequencies. By reversing the calculation order, this method successfully removes the influence of both the linear frequency response and room reflections.

This normalized approach is especially critical for evaluating piezo-MEMS speakers. These silicon-based devices behave very linearly in the lower frequencies, but their sensitivity increases with frequency. Consequently, standard THD equations sometimes can conflate their rising linear acoustic output with non-linear distortion which can result in trying to design around nonlinearities that don’t exist.

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Listen, Inc.: Celebrating 30 Years of Audio Measurement Expertise

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This article celebrates 30 years of Listen, Inc., detailing the company’s journey from its inception in 1995 with the creation of SoundCheck, a software-based audio analyzer. Initially focused on replacing human listeners for end-of-line production testing, the company expanded its reach to research and development (R&D) as its software surpassed expensive hardware solutions. Over three decades, SoundCheck has consistently evolved, adapting to the changing audio landscape with features like multichannel capability and support for modern devices and interfaces.

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Listen, Inc.: Celebrating 30 Years of Audio Measurement Expertise

Back in 1995, I worked as an audio consultant, having recently returned from four years working as an applications engineer for Brüel & Kjær in Denmark. Creating a software based analyzer had been at the back of my mind for a while, but it took a conversation with the president of my consulting client, Sonetronics, to incentivize me to build it. We discussed the possibility of using software-based solutions on his production line, and although I failed to convince him to hire me to develop it, he agreed to buy it if I could deliver a solution within six months.

I worked by day and coded by night to meet the deadline, incorporating ideas I had nurtured for a while such as the stepped sine wave test signal and the HarmonicTrak algorithm. I showcased my product, and with a few minor tweaks, they bought it. I quickly saw the potential for this product and focused all my energy on continuing its development. I added the “sequence editor” a drag-and-drop interface to create customized audio tests, and several more measurement algorithms including higher-order harmonic distortion and normalized distortion measurements.

When I registered my company, Listen, Inc., named the product SoundCheck, and started promoting it, I never imagined that 30 years later, virtually every production line would use software for end-of-line test and these early algorithms would become the industry standard.

Chapters covered:

  • The First Decade (1995-2005)
  • The Second Decade (2005-2015)
  • Our Third Decade (2015 – 2025)
  • Commitment to Innovation

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Standardized Automotive Audio Measurements – audioXpress Article, June 2025

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Making accurate audio measurements in cars is complex and ever-changing as manufacturers incorporate functionality such as spatial audio, sound zones, vibration exciters, and more. Automotive companies, infotainment system subcontractors, consultants, and speaker manufacturers range from extensively testing every aspect of the system to measuring nothing at all. This article, originally published in the June 2025 issue of AudioXpress, discusses how the test configuration proposed by the TC-AA for three basic in-car measurements can also be used for a much larger suite of analyses.

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Standardized Automotive Audio Measurements

The Audio Engineering Society (AES) Technical Committee on Automotive Audio published a white paper in 2023 proposing a standardized measurement configuration for in-car audio systems. This proposal covered three basic measurements: frequency response, Max SPL, and impulsive distortion. However as manufacturers add more complex audio to their cars, more sophisticated acoustic, vibration, electrical, and psychoacoustic measurements are needed.

Many of these measurements can be made with the same equipment configuration recommended by the TC-AA, enabling manufacturers to expand their portfolio of tests to match their precise needs and more completely characterize their audio performance. In this article, Steve Temme demonstrates some of these measurements including:

  • Seat-to-Seat Spectral Uniformity
  • Total Harmonic Distortion (THD)
  • Intermodulation Distortion (IMD)
  • Maximum SPL (Sound Pressure Level) at a fixed distortion percentage (e.g., 10% THD)
  • Impulsive Distortion using perceptual methods

These measurements provide a deeper understanding of audio system performance and help correlate results to human perception of sound inside a vehicle.

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Measuring HDMI Audio

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From its origins in 2002 as a new, smaller connector for HDTV, High-Definition Multimedia Interface (HDMI) evolved continuously over the years to become one of the most widely adopted interfaces. This article provides practical answers on how to perform HDMI audio measurements, dealing with the interface’s multiple options and configurations.

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Measuring HDMI Audio

Measuring HDMI Audio - image of ax articleHow do you measure HDMI audio? This is a question we often hear as HDMI soundbars become more commonplace and the rapid adoption of surround sound and spatial audio systems with televisions continues. While some manufacturers offer expensive custom interfaces to test HDMI devices, there is a much more cost-effective method. Some software-based audio measurement systems can be used with a $100 off-the-shelf interface that enables test signals to be sent via HDMI to a soundbar or surround sound system for measurement. In this article, we discuss how the HDMI protocol handles audio and demonstrate acoustic measurements on a soundbar using Listen SoundCheck software with a commercially available HDMI audio extractor. This method can be extended to a wide range of HDMI connected devices including multichannel surround sound systems.

HDMI Audio
Modern HDMI systems offer Audio Return Channel (ARC) functionality. This allows a single HDMI connection to be used as both an audio input and an output, providing a two-way flow of audio, in addition to video, between devices. This eliminates the need for a dedicated audio cable to connect a soundbar or AV receiver to the television, simplifying configuration and reducing cost and cabling. ARC supports up to six-channel compressed audio and has a maximum bandwidth of 1Mb/second. It supports various audio formats including PCM (2 channel), Dolby Digital (up to 5.1 channel), and DTS Digital Surround (up to 5.1 channel).

A newer version, Enhanced Audio Return Channel (eARC) improves upon ARC with a significant boost in bandwidth and speed, enabling transmission of higher quality audio from a TV to a soundbar or AV receiver. It carries up to 32-channel audio, including eight channels of 24-bit/192kHz uncompressed audio, and supports modern advanced audio formats such as DTS-HD Master Audio, DTS:X, Dolby TrueHD, and Dolby Atmos.

Many audio devices that are used with audiovisual systems, such as soundbars, speakers, gaming headsets, and so forth, are unable to accept an HDMI input with video directly. A small device called an HDMI extractor is commonly used to split the audio and visual HDMI signals so that the audio signal can be played directly on a soundbar or surround sound system. Audio extractors typically cost around $100 and can be purchased online or from electronics or AV stores.

These widely available devices also enable HDMI audio devices to be measured using a software-based audio analyzer. To measure audio, a test stimulus must be sent from the computer to the device under test (DUT). Although soundbars usually feature an HDMI port, as do most computers, typically the device’s audio channels will not be accessible if they are directly connected via an HDMI cable.

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Q&A with Steve Temme – Loudspeaker Industry Sourcebook 2024

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Want to get to know Listen Founder and President, Steve Temme, a little better? Each year, Loudspeaker Industry Sourcebook features interviews with industry leaders in which they ask their opinions on current events, issues and trends in the audio industry. Read what Steve Temme had to say.
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Question 1: How would you describe the market and the industry over the past year? And how did your current business evolve in the past 12 months?

Temme: It’s never a good start to the year when most of your major customers announce massive layoffs and budget freezes in January! However, some of the best innovations are developed during challenging times, and this year has been no exception. Our perceptual measurement drive continued with our new enhanced Loose Particles algorithm for transient distortion detection. We also introduced AudioConnect 2, our portable and budget-friendly 2-channel audio interface, and the MDT-4000 audio measurement turntable, with high-end performance at a very competitive price. Also on a positive note, the return to normal component costs and lead times has relieved a lot of our manufacturing stresses and enabled us to return to full stock levels of all our hardware products.

Question 2: What are the perspectives for your business in the next 12 months?

Temme: Right now, I’m just hoping for a year that does not include a pandemic, increased trade sanctions, supply-chain issues, or a fire at one of our key component suppliers! Joking aside, from adversity comes innovation, and the challenges of the past few years have resulted in the audio industry overflowing with new technologies and applications which is keeping us on our toes with new measurement challenges. One example is the automotive industry – audio measurement is increasingly challenging due to the high channel counts and a vast amount of on-board signal processing combined with many different test requirements including, spatial audio, sound zones, hands-free communications, active noise reduction and more. Similarly, spatial audio presents some exciting measurement challenges as we continue to develop perceptual metrics to locate virtual sound sources and measure spatial audio reproduction accuracy.

Question 3: In reference to your supply chain and the geographical markets in which you do business, what, if any, changes have you made in the way you do business?

Temme: When I visited Shenzhen last year, I was surprised by how much had changed. I was one of very few foreigners, and since my last visit, Chinese brands had replaced most American consumer products – particularly in the automotive industry. Few of our OEM customers have resumed their pre-pandemic travel schedules, leaving far more responsibility for audio product quality in the hands of their contract manufacturers. This, combined with the drive to ‘buy Chinese’ has created a massive surge in factories using locally made, in-house, or even pirated measurement systems with minimal oversight. We’ve worked closely with our customers to provide new tools that help them ensure test integrity without resuming regular travel to China. This includes the ability to ‘lock’ a measurement sequence so that limits, test levels etc. cannot be changed and even the test steps themselves are hidden from the end user. This prevents the test sequence being modified, misappropriated, or re-created on a different test system with unproven results. We also introduced the capability to lock a test sequence to specific verified hardware keys, further ensuring end-to-end test compliance.

 

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Measuring MEMS Microspeakers

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Measuring MEMS microspeakers can be challenging due to their small form-factor, but it is increasingly important as they are now widely available and seeing fast evolution and adoption in true wireless stereo (TWS) earbuds and in-ear monitors (IEM). Accurate measurement is essential to understanding design considerations, as well as ensure product quality. In this article, published in the June 2024 issue of AudioXpress, Steve Temme and Michael Ricci (xMEMS) discuss the challenges of measuring fully piezoelectric MEMS microspeakers and demonstrate how SoundCheck reveals valuable distortion data.

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Introduction to Measuring MEMS Microspeakers Article

Measuring MEMS microspeakers - image of AX articleMEMS microspeakers are driving one of the fastest technological transitions in the miniature speaker market. MEMS transducers first gained widespread attention in the late 2000s with the first commercially available MEMS microphone, and over the course of a decade, they replaced electret microphones in the majority of mobile devices. The MEMS speaker revolution is shaping up for an even faster transition.

Early speakers incorporating MEMS technology were launched in 2014, but it was not until 2021 that the first fully piezoelectric MEMS microspeakers became commercially available. Manufacturers are already rapidly adopting these into TWS and pro-audio IEMs, earning praise from consumers and product reviewers alike, and propelling this technology into the mainstream.

MEMS Speaker Overview
MEMS microspeakers are constructed in an entirely different way from conventional miniature speakers. Rather than using inductive coils and magnets, they rely on a voltage-driven capacitive actuator, and they are entirely manufactured using a monolithic solid-state fabrication process in a semiconductor wafer foundry. This fabrication process delivers much tighter speaker-to-speaker consistency than is possible with a conventional driver made up of an assembly of many moving parts. They offer full-range performance, eliminating crossover networks that introduce complexity and sometimes even phase differences. This is particularly important considering this year’s other big audio trend—spatial audio, where the phase response is critical to accurate reproduction. Piezo-MEMS speakers are also compact in size and low power, making them economical on both space and power consumption. Finally, they are surface-mount technology (SMT) reflowable, offering yield and quality advantages in device manufacturing.

MEMS microspeakers are now commercially available and seeing fast evolution and adoption in true wireless stereo (TWS) earbuds and in-ear monitors (IEM). With the emergence of these small form-factor transducers comes the need to address how to measure its performance and ensure product quality.

While these advantages are leading to rapid adoption in devices such as hearing aids, earbuds, professional in-ear monitors, smart glasses, and more, they are not without their challenges. The
maximum sound pressure level (SPL) in the low frequencies is typically less than is required for a leak-tolerant active noise cancelling (ANC) system compared with conventional headphone drivers, limiting their use for ANC earbuds to a mid/high frequency tweeter in a two-way configuration. However, in recent months, manufacturers have made rapid progress in overcoming these
limitations, thus broadening their applications. For example, xMEMS’ new Cypress Piezo-MEMS speaker, showcased at the recent Consumer Electronics Show (CES), delivers up to 140dB SPL in the low-frequency band—more than sufficient for ANC applications.

The cost of MEMS-driven products is also decreasing as this technology is more widely adopted. While early MEMS earbuds were priced well over $1000, recently launched models such as the Creative Labs Aurvana bring this technology’s high-quality sound to TWS products below a $200 price point. As this technology moves toward becoming the de facto standard, the outlook for this market is positive.

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Transitioning Audio Tests from R&D to the Production Line

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Steve Temme discusses the transition from R&D to production testing in this March 2023 issue of AudioXpress. Production line audio testing poses many challenges such as noisy environments, harsh operating conditions, high throughput, relative limits, and more. In this article, Steve Temme shares his observations and outlines the main considerations to ensure a successful operation.

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Introduction to Production Line Audio Testing Article

Your product design is finalized, your prototypes are close to perfect, and your audio product is ready to move to production. But how do you ensure that the product hitting the retail shelves sounds exactly as you intended?
Your production line is probably thousands of miles away, with time zone and language complications. Pandemic-related restrictions make it hard to visit to configure, supervise, and train factory personnel. Furthermore, production is often outsourced to a contract manufacturer, adding another layer of complexity to both culture and information transfer.
Every production facility has one priority: to build products that meet the specifications with the greatest efficiency and highest yield possible for optimum profitability. Think about what that means for end-of-line tests. Their goal is to have as many units pass as possible. Tests must be fast to avoid slowing down the production line, and the test environment is generally noisy, often with variable temperature and humidity. The quest for high yields and manufacturing efficiency, along with challenging operating conditions and sometimes poor training, can result in unreliable measurements. When this happens, the only loser is you and your brand’s reputation.
I’ll never forget being told about a production line operator who increased pass-rate by opening the test box during measurements so that the factory background noise would mask the high-order harmonics to fool the perceptual Rub & Buzz algorithm. This might improve his yield, but it’s not so good when these products ship to customers! While this is one of the more outrageous violations of end-of-line test protocol, I have also seen many other questionable measurement practices over the years. In this article, I’ll try to de-mystify production tests and look at some simple measures that you can take to ensure a smooth transition.

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Automotive Max SPL Measurements

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Measuring Automotive Max SPL ArticleIn this short article, Steve Temme discusses measurement of automotive Max SPL, and introduces the efforts of the Audio Engineering Society (AES) technical committee working on automotive audio to standardize the way essential attributes of complex automotive audio systems are measured across the industry. He explains why Max SPL measurements are important, defines this measurement, and describes the standardized measurement procedure suggested by the committee. Test configuration and physical setup is discussed, and example results presented.

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Measuring Automotive Max SPL
By Steve Temme Listen, Inc.
I am currently a participant in an Audio Engineering Society (AES) technical committee working group on automotive audio. This diverse group of about a dozen worldwide experts has focused on trying to standardize the way essential attributes of complex automotive audio systems are measured across the industry. Three specific measurements have been our initial focus: Frequency Response, Max SPL, and Impulsive Distortion. The committee’s proposals for measurements were presented for feedback at the AES Fall Online 2021 conference in a session titled “In-Car Acoustic Measurements.”

I presented our work on Max SPL Measurements, Hans Lahti (Harman) presented Frequency Response, and Stefan Irrgan (Klippel) presented Impulsive Distortion; the session was chaired by Jayant Datta. Here, I will describe our proposed method for Max SPL measurements.

Let’s start with why this is important. People need to be able to compare how loud an infotainment system can play in a car— manufacturers like to quote this in specifications, and consumers enjoy bragging rights about the sound level of their car stereo. Max SPL is defined as the maximum sound pressure level (SPL) that a car’s infotainment system can reproduce inside the cabin with the windows, sunroof, and convertible top closed. There are many ways this can be measured, but to keep it simple, two different measurements are recommended—overall Max SPL and Max SPL Spectrum regardless of distortion level. The reason we don’t take into account distortion when we measure the Max SPL is because it is difficult to characterize distortion in a modern-day infotainment system—these devices frequently contain much signal processing, and this makes them unsuitable for playing back the sine wave stimuli that are typically used for harmonic distortion measurements.

First, let’s examine the physical test setup. Our proposed test configuration replicates the position of an average person’s head in the driver’s seat using a precisely and specifically positioned six- microphone array in the driver’s seat. The height and the angle of the seat, the positioning of the microphones with respect to the seat, and the height and the angle of the microphones are clearly defined to ensure standardized measurements across all vehicles.

The sound system settings on the head unit—the tone control and fader—are set to the factory default setting; in most cases this is neutral or flat with no equalization. The head unit’s volume control is set to its maximum level using the volume control knob or digital user interface equivalent (e.g., volume level slider). Overall Max SPL can be measured using a microphone array with the six microphone signals power averaged by analog or digital means and connected to either a conventional or software-based sound level meter that can measure true RMS and be C-weighted, as described in the IEC-61672 standard. However, if a software-based system is used for measuring the Max SPL Spectrum, it is simpler to also measure the overall Max SPL through the software. Figure 1 shows a test configuration that makes both measurements simultaneously using SoundCheck software, and an AmpConnect 621 audio interface.

For both the overall Max SPL and Max SPL Spectrum measurements, a broadband (20Hz to 20kHz) monophonic pink noise stimulus is used. It has a crest factor of 15dB and is played for 30 seconds to make sure the system can sustain that level continuously. This is played at maximum volume to ensure the system is tested at the loudest signal the car will play. The sound source may come from any source—a memory stick, a CD, or Bluetooth from a smartphone or auxiliary line in. The average SPL in dB(C) is measured for 30 seconds. This is called a Leq measurement, and it takes the spatial average of the six-microphone array, power averaged, to get the overall Max SPL level (Figure 2).

The Max SPL Spectrum is measured using a real-time analyzer set to 1/12 octave resolution, 30 second linear averaging time and no waiting. This enables us to measure the level versus frequency irrespective of the human ear’s perception. The Max SPL is recorded at each microphone simultaneously from 20Hz to 20kHz and the power average calculated (Figure 2).

Listen offers a pre-written SoundCheck test sequence that measures both the Max SPL Spectrum and a single, power averaged value for Max SPL in line with the working group’s proposed guidelines. This enables consumers and manufacturers to measure the maximum overall SPL and maximum SPL versus frequency that a car’s infotainment system can reproduce inside its cabin. The sequence uses the method and test configuration with a six-microphone array in either the driver or passenger seats. It takes advantage of Listen’s 6-in, 2-out AmpConnect 621 audio interface, which seamlessly integrates with the software-based multichannel analyzer to measure, display, and average the results from the six microphones in real time, and power average them to calculate Max SPL. This sequence may be downloaded free of charge from Listen’s website. More details about these measurements, and the other measurement proposals developed by the technical committee, will be presented at the 2022 AES International Conference on Automotive Audio, June 8-10, in Dearborn, MI.

 

Further information on the AES Technical Committee on Automotive Audio, including a link to the working group’s draft white paper on can be found here: https://www.aes.org/technical/aa/

More about measuring automotive Max SPL.

Q&A with Steve Temme – Loudspeaker Industry Sourcebook 2022

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Q&A with Steve Temme - Loudspeaker Industry Sourcebook 2022Want to get to know Listen Founder and President, Steve Temme, a little better? Each year, Loudspeaker Industry Sourcebook features interviews with industry leaders in which they ask their opinions on current events, issues and trends in the audio industry. Read what Steve Temme had to say.
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Question 1: How did your current business evolve in the past 12 months and what were the main trends and factors (good and bad) affecting your business?

Temme: I am sure that no one will dispute that these are challenging times! COVID-19, working from home, travel restrictions, global parts shortages, and the AKM fire, which temporarily wiped out one of the world’s largest audio chip vendors, have all played a part in making it a tumultuous year or two. That said, there have been some bright spots. On an industry level, the demand for improvements in communications quality due to continued remote work has diversified measurement opportunities far beyond traditional telecommunication devices into other communication devices, such as smart speakers, Bluetooth speakers, headsets, microphones and more. We’ve thrived on the challenges of developing software features that enable these devices to be accurately measured, such as including the POLQA algorithm and expanding capabilities to facilitate the measurement of Doubletalk and other metrics required for communications standards.

Question 2: What are the perspectives for your business in the next 12 months?

Temme: I believe the next 12 months will continue to be a phase of continual re-adjustment based on changing global situations. Personally, I can’t wait to get back visiting customers and attending events again! While I am sure things won’t be the same as they were back in 2019, there is no substitute for visiting customers in their labs and production facilities where you can truly understand their measurement challenges. Of course, some of the activities that we invested over the past couple of years, such as the development of our online training courses, applications seminars and popular video series, have been so well received that they are here to stay, even as we start to travel again.

Question 3: What were the most exciting developments, technology innovations, and trends happening in your field of interest over the last 12 months?

Temme: This is what I love about audio—there is always so much going on. In my specific area—audio measurement—the most exciting developments are in the area of perceptual measurement. Perceptual measurement metrics are extremely valuable for end-of-line tests as they offer significant impact on yield and waste reduction in a world of ever-shrinking margins. This has been a field of research for Listen, and for me personally, for more than 10 years now. We led the way with our first perceptual metric in 2011, but our recently launched enhanced Perceptual Rub & Buzz (ePRB) algorithm is the first time any perceptual metric has truly delivered the repeatability necessary for widespread end-of-line testing, and it has the potential to make a huge impact, worldwide. Outside of my own company, I am always fascinated by those innovations that will present interesting measurement challenges. Right now, many of these involve spatial and perceptual audio in applications, such as automotive infotainment sound zones and virtual and augmented reality hardware. Communications devices are also posing some interesting measurement challenges as they incorporate increasingly sophisticated digital signal processing in pursuit of higher quality audio.

 

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End of Line Distortion Measurements

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End of Line Distortion Measurements - LIS 2022Steve Temme discusses the importance of detecting manufacturing-induced defects such as Rub & Buzz, Loose Particles, and other distortion measurements during end-of-line testing and explains the various algorithms that are used. He compares conventional and perceptual metrics for the measurement of Rub & Buzz, including Listen’s new enhanced Perceptual Rub & Buzz algorithm, and discusses why it can be beneficial to use both conventional and perceptual measurements in tandem.

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INDUSTRY FEATURES
End-of-Line Distortion Measurements

Steve Temme focuses on various test methods, and introduces Listen’s newest perceptual distortion algorithm, comparing it to other conventional and perceptual techniques in this article about distortion measurements.

It is important to catch speakers with Rub & Buzz and transient distortion defects at the end of the production line, as such defects sound harsh and quickly give the impression of poor quality. These manufacturing-induced distortion defects are easy to screen for, but what exactly should you be measuring? In this short guide to end-of-line distortion measurement, we discuss various test methods, and introduce Listen’s newest perceptual distortion algorithm, comparing it to other conventional and perceptual techniques.

What Causes Rub & Buzz and Loose Particles

Rub & Buzz and Loose Particle faults are pretty much exclusively introduced during the manufacturing process. Rub & Buzz is usually caused by small aberrations in the manufacturing process that make some parts rub or rattle when the speaker is operated, such as off-center voice coils, poorly glued surrounds, or incorrectly trimmed lead wires. This can be a random manufacturing issue with one product, or a drift in production line characteristics over time. Loose particles are caused when foreign particles, such as glue or magnet fragments, become trapped in the gap behind the diaphragm or dust cap during the manufacturing process.

Conventional Detection Methods
Although Rub & Buzz, and Loose Particles sound different to the trained ear than they do to the average consumer, both manifest themselves as an annoying vibration sound that may be more prominent at certain frequencies and worse at higher output levels. Despite this similarity, the detection methods are very different. Rub & Buzz is a periodic distortion effect. Conventionally, it is measured using Higher Order Harmonic Distortion (HOHD) analysis, examining typically the 10th order harmonic and above. These harmonics contribute most significantly to Rub & Buzz as their separation from the fundamental frequency makes them less masked and more easily detected by the ear. There are several widely used measurement methods. A high-pass filter algorithm is common, but has its limitations as it combines all the harmonics into an overall metric, and does not distinguish between periodic and transient distortion. Other methods sequentially measure individual harmonics using a tracking filter that moves from one harmonic to the next. While this technique provides accurate and detailed information on each harmonic, it is not fast enough for use on automated production lines.

 

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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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