AES Section Meeting Reports

Chicago - April 16, 2020

Meeting Topic:

Speaker Name:

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The meeting was introduced and moderated by Andrew Bellavia (Director of Market Development, Knowles Electronics)

Video Recording:

Presentation Slides (PDF):

Many companies wish to add Active Noise Control (ANC) to their wireless music headsets. ANC makes wearing insert earphones more pleasant, and makes the music easier to hear clearly. Unfortunately, most publications on noise cancelling lack practical information needed to make many key design decisions, and the experts are quite reluctant to share their methods. This presentation will help fill some of those gaps, covering many of the factors needed to provide good noise reduction in small headsets. It will cover the basics of ANC operation, then go onto discuss design factors such as headset acoustics and venting, filter design, and transducer selection. Tom will discuss how to keep an ANC system stable across a variety of wearers, dispelling some myths about latency and stability. He will show how to make good use of balanced armature devices in ANC systems, including how to add a tweeter without disrupting stability. The discussion will conclude with a brief description of transparent pass-through operation and some more advanced ANC techniques that adapt the headset to users and certain use cases.

Tom Miller is a Senior Principal Engineer at Knowles Electronics, and has been there for nearly a quarter century. Over those years he has helped to create many of Knowles' balanced armature receiver designs and has been granted over a dozen patents. More recently he has been studying how Knowles microphones and receivers affect system level issues, such as the control of wind noise pickup and active noise cancellation. Tom is a former Regional Vice President of the AES, and has held every local office except treasurer. Back in a previous century Tom obtained a Bachelor's degree in Electrical Engineering from the University of Michigan. Upon graduation, he worked for a dozen years as chief technical engineer of Universal Recording, a major Chicago recording studio in its day. After that, he spent a few years working on signal processing for loudspeakers at International Jensen before moving on to Knowles. In his spare time he creates electronic music under the name Shadreaux, having released several albums on Bandcamp (but selling almost none).

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AES - Audio Engineering Society