Residual echo power estimation for speech reinforcement systems in vehicles

In acoustic echo cancelation systems, some residual echo exists after the acoustic echo canceler (AEC) due to the fact that the adaptive filter does not model exactly the impulse response of the Loudspeaker-Enclosure-Microphone (LEM) path.This is specially important in feedback acoustic environments like speech reinforcement systems for cars where this residual echo can make the system become unstable. In order to suppress this residual echo remaining after the AEC, postfiltering is the most used technique.The optimal filter that ensures stability without attenuating the speech signal depends on the power spectral density (psd) of the residual echo that must be estimated. This paper presents a residual echo psd estimation method needed to obtain the optimal echo suppression filter in speech reinforcement systems for cars.