Comparison of Generalized Sidelobe Canceller Structures Incorporating External Microphones for Joint Noise and Interferer Reduction

In this paper, we compare two extended generalized sidelobe canceller (GSC) structures, which exploit external microphones in conjunction with a local microphone array to improve the noise and interferer reduction. As a baseline algorithm we consider a local GSC using only the local microphones, for which the relative transfer function (RTF) vector of the target speaker is known. To incorporate the external microphones in a minimum power distortionless response beamformer, the RTF vector of the target speaker needs to be estimated. Since the estimation accuracy of this RTF vector depends on the signal-to-interferer ratio, the GSC with external speech references (GSC-ESR) pre-processes the external microphone signals to reduce the interferer. In a simplified extended structure, namely the GSC with external references (GSC-ER) no such pre-filtering operation is performed. Simulation results show that the GSC-ESR structure yields the best results in terms of noise and interferer reduction, especially in adverse conditions.