Full-duplex hands-free man/machine interface often suffers from directional nonstationary interference, such as a competing speaker, as well as stationary interferences which may comprise both directional and nondirectional signals. The transfer-function generalized sidelobe canceller (TF-GSC) exploits the nonstationarity of the speech signal to enhance it when the undesired interfering signals are stationary. Unfortunately, the assumptions leading to the derivation of the TF-GSC are violated when a nonstationary interference is present. In this paper, we propose an adaptive beamformer, based on the TF-GSC, that is suitable for cancelling nonstationary interferences in noisy reverberant environments. We modify two of the TF-GSC components to enable suppression of the nonstationary undesired signal. A modified fixed beamformer (FBF) is designed to block the nonstationary interfering signal while maintaining the desired speech signal. A modified blocking matrix (BM) is designed to block both the desired signal and the nonstationary interference. We introduce a novel method for updating the blocking matrix in double talk scenarios, which exploits the nonstationarity of both the desired and interfering speech signals. Experimental results demonstrate the performance of the proposed algorithm in noisy and reverberant environments and show its superiority over the original TF-GSC.

In this paper, we present a multi-channel acoustic echo canceller that is integrated into the transfer-function generalized sidelobe canceller (TF-GSC). 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. Experimental results demonstrate improved performance compared to cascade schemes of acoustic echo cancellation and adaptive beamforming.