Residual echo filter for enhanced acoustic echo control

This paper presents a method for efficient control of an acoustic echo control (AEC) system. The control is achieved with the help of so-called residual echo filter structure. The residual echo filter can be exploited to provide an accurate estimate of the norm of the system mismatch vector (sometimes also called as an echo coupling factor), which is an essential element for providing advanced control means for the adaptive echo cancellation filters. In addition to the adaptive filter a sophisticated AEC systems usually include echo suppression means to complete and ensure sufficient echo cancellation performance. The residual echo filter may also be utilized to estimate the power spectral density of the residual echo, which is needed to implement the suppression filter. The use of the residual echo filter structure overcomes some weaknesses in the ordinary AEC controlling means and provides enhanced overall AEC performance.