Acoustic echo cancellation in the presence of distorting loudspeakers

Acoustic echo cancellation is usually needed in hands-free telephone systems or in video conference applications. Conventional acoustic echo cancellers (AECs) basically rely on the assumption of a linear echo path. Their performance is then limited in the presence of nonlinearities, like those typically generated in low-quality loudspeakers. The presence of nonlinearities require the adoption of nonlinear AECs. Truncated Volterra filters are usually applied to nonlinear echo cancellation, but the improvements obtained with respect to linear adaptive filters do not justify a computational load of at least O(N²) (like in the case of second-order Volterra filters) and simpler approaches are necessary. In this paper the effect of loudspeaker nonlinearities is first investigated. Then a convenient new nonlinear architecture based on spline adaptive functions with computational cost of O(N) is proposed as an effective alternative to computationally more expensive approaches.