Acoustic Echo Control

Abstract

In this chapter, the authors discuss algorithms for feedback control in handsfree voice communication systems, which use loudspeakers and microphones instead of a telephone handset. At the center of their discussion are adaptive algorithms for acoustic echo cancellation (AEC). AEC is an essential component of high-quality full-duplex handsfree communication devices. AEC is quite a challenging application of adaptive filters and other signal processing techniques. The authors present and discuss the most important algorithms for the adaptation of acoustic echo cancellers in the time and frequency domain, as well as additional measures for echo control. As the acoustic environment may vary with time, the echo canceller has to be implemented as an adaptive filter. Many speech communication devices offer a so-called handsfree mode. Since the echo problem has a profound effect on communication quality, numerous international recommendations and standards have been established to guide the development of handsfree devices.

Authors 2

1. Peter Vary Aachen Institute of Communication Systems

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University, Institute of Communication Systems, Aachen, Germany

2. Rainer Martin

   Ruhr University Bochum

   Affiliation as printed

   Ruhr-Universität Bochum, Institute of Communication Acoustics, Bochum, Germany