ISCA Archive Eurospeech 1993
ISCA Archive Eurospeech 1993

Adaptive gain control and echo cancellation for hands-free telephone systems

Peter Heitkamper, Michael Walker

The combination of adaptive gain control and acoustic echo cancellation can reduce the problems arising with hands-free telephone systems. Using a short-length echo canceller, the acoustic coupling between the loudspeaker and the microphone can be decreased consuming only a small amount of processing power. The quality of the local speech signal is improved and residual echoes are attenuated by means of the adaptive gain control. Attached with the gain control is a simple speech detection method and a cross-correlation estimate, which give information about the speakers5 activities. This information can be used to control the adaptation of the echo canceller. The algorithm was implemented on a digital signal processor and was found to operate well in wide bandwidth of 12kHz in various environments.

Keywords: Hands-free Telephones, Echo Cancellation, Adaptive Gain Control, Speech Processing.