An adaptive nonlinearity solution to the uniqueness problem of stereophonic echo cancellation

The major difference between two-channel and single-channel echo cancellation is the nonuniqueness problem in the two-channel case. In previous work, this nonuniqueness problem has been linked to the coherence between the two incoming audio channels. One proven solution to this problem is to distort the signals with a nonlinear device. In this work, we present an adaptive nonlinear device that incorporates new theoretical connections between the level of nonlinearity and the performance of the echo canceler. Adapting the level of nonlinearity is done in such a way that a pre-specified maximum misalignment is maintained while improving the perceived quality by minimizing the introduced distortion. Moreover, all the ideas presented can be generalized to the multichannel (> 2) case.