Combined inverse filtering and feedback control for robust equalization and distortion reduction in loudspeaker systems

A method for the robust equalization and distortion reduction of loudspeakers is proposed. The proposed method adopts both an infinite impulse response (IIR) inverse filter and a feedback controller. The feedback controller based on model-following control theory is used to force a loudspeaker to move as a linear time-invariant (LTI) system. Accordingly, we expect the inverse filter that is specifically designed for the LTI system to work correctly. Furthermore, nonlinear distortion of a loudspeaker is expected to be reduced. Computer simulation shows that the proposed method achieves more robust equalization of a loudspeaker than inverse filtering alone. In addition, the proposed method simultaneously reduces nonlinear distortion of the loudspeaker.