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

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.