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Every month, audioXpress combines the best educational articles on topic such audio electronics, speaker and headphone design, amplifiers (from tube to Class D), acoustics, practical test and measurement, audio engineering praxis, and standards.
audioXpress provides inside stories on new audio developments, on R&D Stories, the most complete objective reviews of innovative products and software, and selects some of the best DIY audio projects from worldwide experts.
4 From the Editor's Desk
The Multiple Facets of Audio Signal Processing
Editorial By J. Martins, Editor-in-Chief
In a 2014 presentation at the 137th Audio Engineering Society (AES) convention, Paul Beckmann, the founder of DSP Concepts, revealed the results of a search within his LinkedIn network to determine how many people had
"Audio Engineer," "Embedded Software," and "Audio DSP" listed in their profiles. He made a Venn diagram of the results, which showed that very few people included
"Audio DSP" and even less (11 out of a universe of more than 100,000), actually claimed to do all of these three things.
5 Client Index
38 What to Measure for Quality Control of Audio Devices
By Dan Knighten
Audio Precision's Dan Knighten focuses on the practical question of what to measure for the quality control of audio devices, with an emphasis on manufacturing test strategies and objectives. He also shares what measurements reveal about the device under test, offers suggestions for specific measurements, and provides techniques for various devices and scenarios.
42 Testing and Optimizing Strategies for Conference Terminal Equipment
By Hans W. Gierlich
Hans W. Gierlich, of HEAD acoustics, provides some insight into how to evaluate and determine strategies to deal with speech transmission quality, which is especially relevant with most company employees working from home and the trend toward decentralized organizations, remote collaborations, and conferencing services.
50 Earthworks M23R Measurement Microphone
By Stuart Yaniger
Stuart Yaniger reviews the M23R Earthworks measurement microphone, which is the latest omnidirectional model in
Earthworks' infinitely matched series of measurement microphones.
56 Getting Started with Automotive Audio Bus (Part 2)
Understanding A2B Features
By Brewster LaMacchia
In Part 2 of this article series Brewster LaMacchia examines how certain optimizations for the automotive applications must be accounted for when targeting broader audio applications. He also includes a look at analog phantom power and how A2B provides that feature in a digital system.
62 Ultra-Low Distortion Microphone Buffer Amplifier (Part 2)
Simulations and Measurements
By Michel Nieuwenhuizen
In the second part of his article, Michel Nieuwenhuizen shows the results of the simulations and the measurements. He also compares the performance of his own circuit with that found in many Chinese condenser microphones (the
"Schoeps" based circuit).
Market Update — DSP Products And Applications
8 Real-Time DSP, Edge Processing, and Artificial Intelligence
By J. Martins and Mike Klasco
This year's digital signal processing market update highlights solutions and platforms that are now able to run extremely intense computational requirements in real time, as required by consumer applications (e.g., voice detection and acoustics optimizations). Increasingly, these platforms are evolving in large scale, targeting the ability to run artificial intelligence inference directly on-device.
24 The Evolution of Audio DSPs
By Youval Nachum
CEVA's Senior Product Marketing Manager, Youval Nachum, discusses how DSP technology has evolved, its impact on the user experience, and what the future of DSP has in store for us.
Columns: Sound Control
28 Electroacoustical Testing
Time-Domain and Distortion
By Richard Honeycutt
34 Simple Improvements to Legacy Audio DAC Output
Interfaces Using Op-Amps
By Michael Steffes
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