AES Section Meeting Reports

University of Massachusetts-Lowell - February 27, 2013

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Tonight, Alex Case, Assistant Professor of Sound Recording Technology and UML AES faculty advisor, gave a lecture on distortion to a packed house. He started by defining distortion, showing us that without any distortion, a graph on input versus output amplitude should yield a single linear slope. He used similar graphs to introduce various types of distortion: hard clipping, soft clipping, asymmetric amplitude axis distortion, etc.

Case continued to explain that adding distortion will result in the addition of harmonic content. By showing clips taken from a spectral analysis program, we saw what the frequency content of various instruments looked like before and after added distortion. Using a light touch of distortion, Case suggested, may be a great way to make a sound source stick out in a mix without needing to increase volume. Performance dynamics were also brought into the discussion of distortion. By coaxing an instrumentalist into a more dynamic performance, you can set your threshold for distortion fairly high, making sure only the peaks of the performance are affected. When this is done before volume leveling, the extra harmonic content will remain after leveling, making certain parts of the performance stick out more than others. We got to hear an example of how this technique worked on an electric guitar performance, and saw what it looked like through the spectral analysis program.

Alex also mentioned many different strategies for obtaining distortion through gain, compression and/or through coaxing different types of analog and digital devices. He reminded us that as there are many different ways to create distortion, and vast collections of tools and plug-ins that can do it for us, the most important tool is our own ears. Distortion can be a tempting effect, but is easily overdone.

We'd like to thank Alex Case for taking time out of his incredibly busy schedule to talk with us, and for making his presentation informative for audio students at all levels of experience.

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AES - Audio Engineering Society