Digital Compensation of Nonlinear Distortion in Loudspeakers

Practical loudspeakers are nonlinear transducers, i.e. the acoustic output is not a linear representation of the electrical input signal. In this paper two loudspeakers are considered; a loudspeaker for reproduction of low frequencies (woofer) and a horn loudspeaker. Instead of improving the behavior of the two transducers by constructional means we apply a feedforward nonlinear digital inverse circuit. Results of a Volterra compensator for the woofer show a significant reduction of the second order harmonics at low frequencies, leaving higher order distortions unchanged. To the horn loudspeaker a more direct method is applied. This loudspeaker suffers from distortions caused by the adiabatic behavior of the air volumes in the compression driver. With this compensator we obtain a reduction of harmonic distortion, in the frequency span from 600 to 1100 Hz.