The AAS​-​4 System

by Greg Surges

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The recordings on "The AAS-4 System" document the use of a novel signal processing technique in which time-varying allpass filters are placed into feedback networks, producing synthesis structures capable of producing interesting emergent sonic behaviors.

Ideas from the field of computational aesthetics are employed to allow a large system built from these synthesis structures to become “aesthetically aware.” Many theories about computational aesthetics center around a favorable balance between order and complexity in a stimulus - a successful artistic work is neither too orderly nor too complex. Using a model of human perception based on the “mere exposure” effect, which describes how listener appreciation and boredom change as they experience repeated exposure to a stimulus, the system autonomously determines when and how to modify its own parameters to avoid repetitions that may lead to boredom in listeners.

The result, created over three years of research and development, are a series of fully generative compositions, synthesized and structured completely in software.

The AAS-4 System is described in greater detail in "Generative Audio Systems: Musical Applications of Time-Varying Feedback Networks and Computational Aesthetics," available at


released January 18, 2016



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Greg Surges Milwaukee, Wisconsin

Greg Surges makes electronic music, software, and hardware. His work has been released on the Stasisfield, Petcord, Wandering Ear, and Digitalbiotope labels, and he is currently a PhD student at the University of California, San Diego. Previously, he earned a MM in Music Composition at the University of Wisconsin – Milwaukee. He currently lives in San Diego, CA with his wife and cat. ... more

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