Position independent close-talking microphone

Abstract

Close-talking microphones are required for speech pick-up in high noise environments and are based on the assumption that unwanted noise sources are distant from a desired nearfield source. Common close-talking microphones in use today have to be carefully oriented relative to the desired nearfield source. To address this problem, a new close-talking microphone array is proposed that is orientation-invariant with respect to the attenuation of farfield noise sources. It is shown that by appropriate processing of the close-talking microphone array signals, one can adaptively compensate for the distance and orientation of the microphone for a nearfield source. The proposed close-talking array is based on an spatially orthonormal decomposition of the soundfield for a nearfield source. It consists of four or more pressure microphones that are mounted in the surface of a rigid sphere with a diameter on the order of a centimeter. Finally, it is shown that decomposing the soundfield into spatially orthonormal modes leads to a computationally efficient implementation.