Adaptive noise abatement system

Abstract

Devices and methods for minimizing multifrequency acoustic or electromagnetic noise that is propagated from its source to a remote region where the noise is to be abated by adaptive means are described herein. The noise minimization is achieved by sampling a noise, synthesizing from this sample a counternoise, the source of which is close to the noise source, and allowing the counternoise to propagate toward said region such that the noise and counternoise cancel each other as they arrive at said region. A closed-loop control is used to adjust the amplitude and time delay, or phase in case of monochromatic noise, of the counternoise during the synthesis, until the residual noise at said region becomes zero. For closed-loop control, the residual noise is transmitted back to the counternoise source by a communication link so that it can be used for said synthesis of the counternoise. The closed-loop control maintains the noise null at said region, even when the distance between the noise and said region changes with time.

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