Development of dynamic loudspeakers modified as incident pressure sources for noise reduction in a double panel structure

This paper presents a modified loudspeaker source for decentralized feedback cavity control in a double panel structure to reduce the noise transmission. The double panel structure con-sists of two panels with air in between and offers the advantages of low weight, low sound transmission at high frequencies, and thermal insulation. The main issues of the double panel structure are the resonance of the cavity and the high noise transmission at low frequencies. Many papers have discussed applying active structural acoustic control to the panels or active noise control to the cavity. In our previous study, we considered the resonance of the panels and the cavity simultaneously and numerically compared various decentralized structural and cavity feedback control strategies basing on identical control stability margins. Cavity control by loudspeakers, which are modified to operate as incident pressure sources, was found to-provide the largest noise reduction. The incident pressure source loudspeaker can be realized by using a dynamic loudspeaker, a microphone, and a velocity sensor with a feedforward controller. In this paper, experimental results of a one dimensional realization with a feed-forward controller are presented.