Abstract
An acive sound absorbing device unit of the transmission noise through a wall, using a plate planewave speaker as the secondary sound source, was developed toward effective suppression of aircraft interior noise. The controller was designed using reference accelerometer attached on the wall, and based on the Filtered-x LMS algorithm, its system identification was in advance performed so as to minimize sound level at one observation point, and then act as an off-line controller. At first, control effects were estimated by the numerical analyses using the system model identified from the actual experimental devices. Then, active sound absorbing experiments were performed with band limited white noise applied to the unit, and it was shown that enough control effects were obtained at plural observation points located in three dimensional space.
