Hersh Acoustical Engineering, Inc.

Larry Heidelberg

Alan S Hersh

Bruce E Walker

The present invention is an active-control system for attenuating noise in a duct having a fluid flow. An array of stators having a longitudinal length is positioned axially within the duct. A first array of sound sources capable of generating spinning mode sound and is positioned a distance upstream of a first plane defined by the upstream-most portion of the stators, relative to the fluid flow. The upstream distance is less than the longitudinal length of the stators. A second array of sound sources capable of generating spinning mode sound and is positioned a distance downstream of a second plane defined by the downstream-most portion of the stators, relative to the fluid flow. The downstream distance is less than the longitudinal length of the stators. A controller causes the first and second arrays of sound sources to generate sound including spinning mode sound such that it cancels a portion of the noise within the fluid flow that passes through the stators.

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Lakewood, OH, United States of America

Larry Heidelberg