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1Department of Electrical and Computer Engineering, Curtin University of Technology, Perth, WA 6845, Australia 2College of Engineering & Computer Science, The Australian National University, Canberra, ACT 0200, Australia 3 Institute of Physics, Signal Processing Group, University of Oldenburg, 26111 Oldenburg, Germany 4 School of Engineering, Bar-Ilan University, 52900 Tel Aviv, Israel 5Department of Electrical and Electronic Engineering, Imperial College, London SW7 2AZ, UK 6Microsoft Research, USA

1Digital Signal Processing Group, Ruhr-Universitat Bochum, 44780 Bochum, Germany 2 Siemens Audiologische Technik GmbH, 91058 Erlangen, Germany 3 Institute for Human-Machine Communication, Technische Universitat Munchen, 80333 Munchen, Germany 4 Signal Processing Laboratory, Western Australian Telecommunications Research Institute (WATRI), Crawley, WA 6009, Australia 5Centre for Applied Hearing Research, Acoustic Technology, Department of Electrical Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark 6Multimedia Communications and Signal Processing, Universitat Erlangen-Nurnberg, 91058 Erlangen, Germany

This paper investigates the problem of enhancing a single desired speech source from a mixture of signals in multispeaker environments. A beamformer structure is proposed which combines a fixed beamformer with postfiltering. In the first stage, the fixed multiobjective optimal beamformer is designed to spatially extract the desired source by suppressing all other undesired sources. In the second stage, a multichannel power spectral estimator is proposed and incorporated in the postfilter, thus enabling further suppression capability. The combined scheme exploits both spatial and spectral characteristics of the signals. Two new multichannel spectral estimation methods are proposed for the postfiltering using, respectively, inner product and joint diagonalization. Evaluations using recordings from a real-room environment show that the proposed beamformer offers a good interference suppression level whilst maintaining a low-distortion level of the desired source.

1 School of Engineering, Bar-Ilan University, Ramat-Gan, 52900, Israel 2 INRS-EMT, University of Quebec, 800 de la Gauchetiere Ouest, Montreal, QC, Canada H5A 1K6 3 Institute of Audiology and Hearing Science, University of Applied Sciences, Oldenburg/Ostfriesland/Wilhelmshaven Ofener Street 16, 26121 Oldenburg, Germany 4Department of Electrical Engineering, Technion — Israel Institute of Technology, Technion City, Haifa 32000, Israel 5Department of Electrical Engineering (ESAT-SCD), Katholieke Universiteit Leuven, Kasteelpark Arenberg 10, 3001 Leuven, Belgium 6 Institute of Communication Acoustics, Ruhr-Universitaet Bochum, 44780 Bochum, Germany 7Western Australian Telecommunications Research Institute, The University of Western Australia, 35 Stirling Hwy, Crawley, 6009, Australia