Active attenuation of acoustic noise using adaptive algorithms

The authors consider the general conditions for phase cancellation of broadband acoustic noise emanating from compact sources. From this, the characteristics, geometry, and requirements to obtain complete cancellation of signals were obtained. By making use of these relationships to analyze an active noise-control system, an expression for the required controller was obtained. Several frequency-domain adaptive filter designs were developed. Comparative computer simulations of these filters were given and revealed interesting points concerning the different structures. Finally, the real-time implementation to a synthetic source was examined, and the performance using variable single tones and broadband signals was investigated. The performance was further investigated by application to the attenuation of the exhaust noise of a 100-cm/sup 3/ motorcycle.<>