ACTIVE REDUCTION OF RADIATED NOISE FROM A BAFFLED PISTON USING A VOLUME VELOCITY, FEEDFORWARD CONTROLLER

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 distri buting an array of control devices over the surface of the radiating s tructure. Each device consists of a motion-sensing mechanism, an analo g control circuit, and a loudspeaker. The loudspeaker is driven such t hat it reduces the volume velocity of the radiating structure within i ts close proximity. This paper briefly presents the theory behind this approach as well as controller design issues. Finally, a discussion o f the experimental verification of this concept using a IO-in. uniform ly vibrating circular plate (i.e., a baffled piston) and a single nois e-control device is given. Broadband (50-500 Hz) sound reductions in t he range of 10-20 dB were achieved over a wide spatial area.