A Novel Volterra-Wiener Model for Equalization of Loudspeaker Distortions

Future mobile multimedia devices such as videophones will require high playback levels where devices are used at an arm´s length from the listener. When small loudspeakers are driven at high playback levels the nonlinear characteristics of these speakers become a major source of sound degradation and can drop the MOS score by as much as one point. Conventional approaches to loudspeaker compensation based on the Volterra model improve the sound quality only at low playback levels and may introduce more distortion at high playback levels. This paper presents a new Volterra-Wiener model that is a better match to the loudspeaker response and lends itself to having an exact nonlinear inverse. Simulations and real measurements show that compensation based on the new model greatly reduces the linear and nonlinear distortions of small loudspeakers mounted in the cell phones. Objective and subjective evaluations show drastic improvements (0.8 PESQ) in the sound quality