A circular microphone array beamformer based on spherical harmonics

A circular microphone array that can easily steer its beampattern(s) to any angle in the horizontal plane around the array would be an attractive microphone array for room audio conferencing. An elegant solution to this problem to design a modal beamformer based on circular harmonics. However, a modal beamformer based on circular harmonics suffers from the loss of control of the beampattern out of the plane of the array. We will present a modified modal beamformer for the circular array that is based on spherical harmonics. This approach allows full control of the beampattern and maintains the efficient steerability known from modal beamformers. Measurements of a specific implementation with 16 sensors will be presented.