Compensation of loudspeaker nonlinearity in acoustic echo cancellation using raised-cosine function

The nonlinearity of a power amplifier or loudspeaker in a large-signal situation gives rise to a nonlinear distortion of acoustic signal. A conventional acoustic echo canceller using linear adaptive filters is not able to eliminate the nonlinear echo component. In this brief, a novel nonlinear echo cancellation technique is presented by using a nonlinear transformation in conjunction with a conventional linear adaptive filter. The nonlinear transformation is derived from a raised-cosine function and is exploited to compensate for the nonlinearity of a loudspeaker. The transformation parameters are updated using the normalized least mean square algorithm according to the unknown nonlinear characteristic of the loudspeaker. Computer simulations show that the proposed method yields, in general, a satisfactory cancellation performance while having a very low computational complexity.