Beamforming of circular microphone array with sound absorbent cylinder

Microphone array technology is an area which has generated a lot of interests in recent years. In this paper, a novel beamforming approach using microphone array mounted on the surface of a sound absorbent cylinder is discussed. By introducing of the sound absorbent cylinder with appropriate selected material acoustic characteristics, the “virtual aperture” of the circular array can be enlarged thereby achieving the better beamforming performance. We first introduce an acoustic cylinder scattering model to provide a theoretical background. Subsequently, we derive the steering vector of the circular array outfitted with the sound absorbent cylinder based on the acoustic field model. The impact of the acoustic impedance to the beamforming accuracy is assessed. An acoustic impedance optimization criteria is developed to enhance beamforming performance. Numerical simulations are conducted to evaluate the theoretical results achieved.