Novel schemes for nonlinear acoustic echo cancellation based on filter combinations

Nonlinear acoustic echo cancellers (NLAEC) are becoming increasingly important in hands-free applications. However, in some situations, an NLAEC is inferior to a linear AEC, especially when the channel generates a negligible (or no) nonlinear echo. In general, the ratio of the linear to nonlinear echo signal power is unknown a priori, and will vary over time, thus making it difficult to know if an NLAEC would improve or degrade the cancellation. In this paper, we present two novel solutions to this problem based on the adaptive combination of linear and nonlinear echo cancellers. Both solutions perform efficiently regardless of the level of nonlinear echo. The benefits and robustness of both schemes are illustrated by experiments using Laplacian colored noise and speech input signals.