Active noise control at the source

Abstract

An active noise control system was investigated to control noise at its source. Much of the previous work on active noise attenuators employed cancellation of sound with sound. In the present work, the radiated acoustic energy was attenuated by counter exciting the radiating surfaces. Appropriate counter excitation was achieved by using an adaptive control mechanism consisting of a feedback control circuit, sensors and exciters. Separate control systems for attenuation of steady-state and random noise sources are described. Active noise control was also applied to increase the transmission loss of panels, particularly at low frequencies which requires only a modest amount of counter-excitation energy. Feasibility of these systems are described through theoretical development of the models and experimental results. [Work supported partially by Bendix Advanced Technology Center.