Two Microphone Array MVDR Beamforming with Controlled Beamwidth and Immunity to Gain Mismatch

Conference: IWAENC 2012 - International Workshop on Acoustic Signal Enhancement
09/04/2012 - 09/06/2012 at Aachen, Germany

Proceedings: IWAENC 2012

Pages: 4Language: englishTyp: PDF

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Kerner, Yair; Lau, Harry (Conexant Systems, Inc, 4000 MacArthur Blvd., Newport Beach, CA 92660, USA)

This paper deals with applications that accomplish spatial filtering using two element microphone arrays and employing Minimum Variance Distortionless Response (MVDR) beam-forming. The frequency response of the microphones has limited accuracy, leading to mismatch between the microphone elements in both gain and phase, especially when making use of mass-production low-cost microphones. We introduce a method for controlling the beamwidth of the main lobe, bringing it to a specified constant width over a wide range of frequencies, thus helping to reduce sensitivity to phase mismatch. We also show a modified MVDR formula that remedies the susceptibility of the algorithm to gain mismatch. Index Terms — Microphone array, beamforming, minimum variance distortionless response (MVDR), frequency invariant beamwidth, microphone mismatch, phase mismatch, gain mismatch