Bolt Beranek and Newman Inc.

Bill Gene Watters

Thomas R Horrall

Ronald Bruce Coleman

Roy Allen Westerberg

Michael Nacey

An active noise and vibration control system is constructed such that the residual signal from the residual sensor is fed back into the controller and used to generate the probe signal. Measurements of the residual signal are used to create a related signal, which has the same magnitude spectrum as the residual signal, but which is phase-uncorrelated with the residual signal. This latter signal is filtered by a shaping filter and attenuated to produce the desired probe signal. The characteristics of the shaping filter and the attenuator are chosen such that when the probe signal is filtered by the plant transfer function, its contribution to the magnitude spectrum of the residual signal is uniformly below the measured magnitude spectrum of the residual by a prescribed amount (for example, 6 dB) over the entire involved frequency range. The probe signal is then used to obtain a current estimate of the plant transfer function.

Active noise and vibration control system accounting for time varying

The invention involves the use of a plurality of incoherent noise generators distributed, in one embodiment, along ceilings in open-plan and partitioned office spaces and the like, to diffuse masking sound energy through acoustical tile and other false ceiling structures while tailoring the same for speech privacy results, by providing a uniform, delocalized and incoherent masking sound space.

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Gloucester, MA, United States of America

Bill Gene Watters