A robust adaptive beamformer for microphone arrays with a blocking matrix using constrained adaptive filters

This paper proposes a new robust adaptive beamformer applicable to microphone arrays. The proposed beamformer is a generalized sidelobe canceller (GSC) with a new adaptive blocking matrix using coefficient-constrained adaptive filters (CCaF's) and a multiple-input canceller with norm-constrained adaptive filters (NCAF's), The CCAF's minimize leakage of target signal into the interference path of the GSC, Each coefficient of the CCAF's is constrained to avoid mistracking. The input signal to all the CCAF's is the output of a fixed beamformer, In the multiple-input canceller, the NCAF's prevent undesirable target-signal cancellation when the target-signal minimization at the blocking:matrix is incomplete. The proposed beamformer is shown to be robust to target-direction errors as large as 20 degrees with almost no degradation in interference-reduction performance, and it can be implemented with several microphones, The maximum allowable target-direction error can be specified by the user, Simulated: anechoic experiments demonstrate that the proposed beamformer cancels interference by over 30 dB. Simulation with real acoustic data captured in a room with 0.3-s reverberation time shows that the noise is suppressed by 19 dB, In subjective evaluation, the proposed beamformer obtains 3.8 on a five-point mean:opinion score scale, which is 1.0 point higher than the conventional robust beamformer.