Sound field equalization by active acoustic impedance control

This study examined sound field equalization using active control. The specific acoustic impedance, the ratio of sound pressure and particle velocities were adopted as a source of control. Providing the impedance in the aimed direction was controlled to be the characteristic impedance of the medium, the propagating plane wave in any particular direction was expected. In addition, the directional characteristic of the sound propagation was also controlled by adjusting the weight of ratios of pressure and velocity in three orthogonal directions. The results of numerical simulations indicated the potential efficiency of the proposed method. Furthermore, results of subjective experiments showed the possibility of the proposed control changing the perceived direction of the incoming sound.