Active sound field equalization

The concept and the preliminary examination of active sound field equalization are presented. As well known, active control scheme is mostly used for suppressing the sound pressure at certain points. In our method, however, the sound pressure and the particle velocity are adopted as the control quantity. The acoustic intensities or the specific acoustic impedances at plural points are then modified to control the directional characteristics of the sound field in the enclosure. As a result, the intensity controller changes the direction of standing waves. On the other hands, the impedance controller shows the tendency to yield the propagating waves in desired direction. Both methods show potentials to equalize irregularities of the sound field due to the strong acoustic modes.