Method and device for reducing multi-channel acoustic echo and adapting sound to space conditions

The present invention relates to a method and a device for reducing multi-channel acoustic echo and restoring auditory perspective or "adapting sound to space". It finds a particularly important application in systems for digitally transmitting sound signals on several transmission channels between a local site and one or more remote sites, each site having several microphones and several loudspeakers. Such systems are referred to as "multi-channel" systems with regard to the sound take (the sound is picked up by several microphones), transmission (on several channels) and sound restoration (by means of several loudspeakers). In order to reduce acoustic echo and restore stereophonic sound in a digital transmission system of sound signals on multiple transmission channels, between a local site and one or several remote sites, comprising several microphones and loudspeakers, the method consists in the following steps: computing a weighting factor to be applied to each microphone signal before emitting, based on two attenuation factors computed from the microphone and loudspeaker signals; transmitting on each transmission channel the linear combination of weighted microphone signals; computing a weighting factor to be applied to each loudspeaker signal; and emitting on the loudspeaker the linear combination of transmitted, weighted signals.