Joint noise reduction and acoustic echo cancellation using the transfer-function generalized sidelobe canceller

Man machine interaction requires an acoustic interface for providing full duplex hands-free communication. The transfer-function generalized sidelobe canceller (TF-GSC) is an adaptive beamformer suitable for enhancing a speech signal received by an array of microphones in a noisy and reverberant environment. When an echo signal is also present in the microphone output signals, cascade schemes of acoustic echo cancellation and TF-GSC can be employed for suppressing both interferences. However, the performances obtainable by cascade schemes are generally insufficient. An acoustic echo canceller (AEC) that precedes the adaptive beamformer suffers from the noise component at its input. Acoustic echo cancellation following the adaptive beamformer lacks robustness due to time variations in the echo path affecting beamformer adaptation. In this paper, we introduce an echo transfer-function generalized sidelobe canceller (ETF-GSC), which combines the TF-GSC with an acoustic echo canceller. The proposed scheme consists of a primary TF-GSC for dealing with the noise interferences, and a secondary modified TF-GSC for dealing with the echo cancellation. The secondary TF-GSC includes an echo canceller embedded within a replica of the primary TF-GSC components. We show that using this structure, the problems encountered in the cascade schemes can be appropriately avoided. Experimental results demonstrate improved performance of the ETF-GSC compared to cascade schemes in noisy and reverberant environments.