Active Reduction of Radiated Noise From a Baffled Piston Using a Volume Velocity, Feedforward Controller

Abstract

A new active noise-control technique has been developed for control of low-frequency sound generated by vibrating surfaces which is based on minimizing the volume velocity. Noise reduction is achieved by distributing an array of control devices over the surface of the radiating structure. Each device consists of a motion-sensing mechanism, an analog control circuit, and a loudspeaker. The loudspeaker is driven such that it reduces the volume velocity of the radiating structure within its close proximity. This paper briefly presents the theory behind this approach as well as controller design issues. Finally, a discussion of the experimental verification of this concept using a 10-in. uniformly vibrating circular plate (i.e., a baffled piston) and a single noise-control device is given. Broadband (50–500 Hz) sound reductions in the range of 10–20 dB were achieved over a wide spatial area.