Active Reduction of Nonlinear Loudspeaker Distortion

Electrodynamic loudspeakers have inherent nonlinearities generating harmonic and intermodulation distortion in the reproduced sound. Some applications of active noise control require loudspeakers having low weight, small size, high efficiency to produce amplitudes at low frequencies. In these cases the signal distortions produced by the loudspeaker’s nonlinearities impair the compensation of the primary sound. However, recent activities in loudspeaker research have developed physical models for the nonlinear mechanisms. They are the basis for digital controllers which compensate actively for loudspeaker distortion by preprocessing the electric input signal inversely. This paper gives a summary of this work and shows possible applications to active noise control.