Adaptation of a memoryless preprocessor for nonlinear acoustic echo cancelling

Journal article
(Original article)

Publication Details

Author(s): Stenger A, Kellermann W
Journal: Signal Processing
Publisher: Elsevier
Publishing place: Amsterdam, Netherlands
Publication year: 2000
Volume: 80
Journal issue: 9
Pages range: 1747-1760
ISSN: 0165-1684


Acoustic echo cancellers (AECs) in today's hands-free telephones rely on the assumption of a linear echo path. However, low-cost audio equipment or constraints of portable communication systems cause nonlinear distortions in the loudspeaker and its amplifier, which limit the echo reduction of linear AECs. Such an echo path can be modelled by a memoryless nonlinear function preceding the linear FIR filter. Algorithms for joint adaptation of both stages and stepsize normalizations are derived. As examples for the preprocessor a hard-clipping curve and a polynomial are considered. Fast convergence of the latter is achieved with signal orthogonalization or RLS adaptation. Adaptation stepsize control mechanisms are derived using a novel system distance measure. Experiments under adverse conditions and with real hardware demonstrate robust convergence with both models, and an echo reduction improvement by up to 10 dB at amplitude peaks. For a straightforward implementation, computational cost is increased by factor 1.5-4.5 compared to a linear AEC, but ways for complexity reduction are outlined.

FAU Authors / FAU Editors

Kellermann, Walter Prof. Dr.-Ing.
Professur für Nachrichtentechnik

How to cite

Stenger, A., & Kellermann, W. (2000). Adaptation of a memoryless preprocessor for nonlinear acoustic echo cancelling. Signal Processing, 80(9), 1747-1760.

Stenger, Alexander, and Walter Kellermann. "Adaptation of a memoryless preprocessor for nonlinear acoustic echo cancelling." Signal Processing 80.9 (2000): 1747-1760.


Last updated on 2018-26-12 at 20:50