Tag Archive for: THD

Steve Temme Featured on THD Podcast (Part 2) – Transient Distortion and more

In the second of a 2-part series on the THD Podcast, Steve Temme continues his discussion about why its important for engineers to be able to correlate audio measurements to audibility. He demonstrates Listen’s latest transient distortion algorithm, which offers the unique ability to listen to the recorded waveform with the stimulus removed so that just the distortion artifacts can be heard. This aids understanding of the measurement and makes it very easy to set limits.

THD Podcast #92: Steve Temme discusses Transient Distortion Measurement (Loose Particles)

Additional Resources for Transient Distortion Measurement

All about the Transient Distortion measurement algorithm discussed in this Podcast.

More about SoundCheck’s audio measurement algorithms.

 

More about Steve Temme and the History of Listen, Inc.

SoundCheck Innovation Timeline – highlights of Listen’s product and algorithm introductions.

Reflections on Listen’s 25th Anniversary (2020) – Reprint of an article from Loudspeaker Industry Sourcebook.

 

About the THD Podcast

The Total Harmonic Discussion / the THD Podcast, hosted by Dave Lindberg and Simon Weston, is a weekly discussion on audio and headphone technologies and the people who bring the technology to market. All episodes can be found on its Youtube Channel, and it’s also available on Spotify, Amazon Music, iHeartRadio, Rumble, BitChute, Limited, Apple, and Google.

 

Steve Temme Featured on THD Podcast – Perceptual Distortion and More

Steve Temme recently featured on the THD Podcast. In this engaging episode, he discusses his 30+ year career in audio measurement and some of the changes he’s seen in that time. He also talks about the importance of understanding measurements and being able to correlate measurements to audibility. He also demonstrates the latest in perceptual distortion measurement algorithms, and explains how they improve production line yield while still maintaining product quality.

THD Podcast #91: Steve Temme discusses correlation of audio measurements with audibility

Additional Resources for Perceptual Distortion Measurement

All about the enhanced Perceptual Rub & Buzz measurement algorithm discussed in this Podcast.

More about SoundCheck’s audio measurement algorithms.

 

More about Steve Temme and the History of Listen, Inc.

SoundCheck Innovation Timeline – highlights of Listen’s product and algorithm introductions.

Reflections on Listen’s 25th Anniversary (2020) – Reprint of an article from Loudspeaker Industry Sourcebook.

 

About the THD Podcast

The Total Harmonic Discussion / the THD Podcast, hosted by Dave Lindberg and Simon Weston, is a weekly discussion on audio and headphone technologies and the people who bring the technology to market. All episodes can be found on its Youtube Channel, and it’s also available on Spotify, Amazon Music, iHeartRadio, Rumble, BitChute, Limited, Apple, and Google.

Amplifier THD+N Sequence

This sequence measures an audio amplifier’s Frequency Response, Gain, THD, THD+Noise, and Self-noise. It accomplishes this by playing a 1/3rd octave sine sweep through the amplifier. A HarmonicTrak™ analysis step calculates the fundamental frequency response curve as well as the distortion plots. The sequence then records and analyzes a spectrum of the amplifier’s self-noise.

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Measuring Max SPL versus Frequency

This sequence measures the Max SPL of a transducer versus frequency that a device can play back with acceptable distortion. It is particularly valuable for designers using DSP algorithms to optimize the performance of their speakers.

It characterizes the Max SPL of a transducer by setting limits on specific metrics (THD, Rub & Buzz, Perceptual Rub & Buzz, Input Voltage and Compression) and then driving the transducer at a series of standard ISO frequencies, increasing the stimulus level until the one of the limits is surpassed. The sequence begins by measuring the frequency response and impedance of the DUT. The user is asked if they wish to use the -3dB from resonance frequency as the test Start Frequency or manually enter another value. The user is then prompted to enter a Stop Frequency, initial test level and limit values for the metrics of interest. The sequence then plays the stimulus Start Frequency in a loop, increasing the level +3dB with each loop iteration until one of the limits is exceeded.  The stimulus level is then adjusted -3dB and the sequence continues to a second loop which increases the stimulus level +0.5 dB with each loop iteration until the limit is exceeded. At this point, the limit results are saved to an Excel file, the stimulus frequency is incremented by a constant multiplication step and the process is repeated until the Stop Frequency is achieved. Every time the main loop is completed, the individual SPL and Stimulus Level x-y pairs are concatenated to master curves. At the end of the sequence, the Max SPL and Stimulus Level curves are autosaved in .dat format.

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A New THD+N Algorithm for Measuring Today’s High Resolution Audio Systems

In this paper, a mathematical definition of Total Harmonic Distortion + Noise suitable for testing high-resolution digital audio systems is presented. This formal definition of the “distortion analyzer” mentioned in AES17 defines THD+N as the RMS error of fitting a sinusoid to a noisy and distorted sequence of measurements. We present the key theoretical result that under realistic conditions a modern THD+N analyzer is well-described by a Normal probability distribution with a simple relationship between relative error and analysis dwell time. These findings are illustrated by comparing the output of a commercial distortion analyzer to our proposed method using Monte Carlo simulations of noisy signal channels. We will demonstrate that the bias of a well-designed distortion analyzer is negligible.

Authors: Alfred B. Roney The Mathworks, Inc. (formerly Listen, Inc.) Steve Temme, Listen, Inc.
Presented at AES 2018, New York, NY.

Full Paper