A Frequency Invariant Broadband Beamformer Based on Directional Microphone Array

The performance of a frequency invariant broadband beamformer based on an omnidirectional microphone array will suffer great reduction at low frequencies. To overcome it, in this paper, we explore the potential of directional microphone arrays to provide more degrees of freedom to the frequency invariant broadband beamformer design. On this basis, a more general expression of the optimal weights is given regardless of the microphone type or the array geometry. Several examples are presented to show that the proposed beamformer can bring about comparatively superior performance in robustness, directivity and frequency invariance.