Improved directivity of spherical microphone arrays

Cardoso, Clara and Nelson, Philip (2012) Improved directivity of spherical microphone arrays. In International Congress on Noise Control Engineering 2005, INTERNOISE 2005. vol. 3, Curran Associates Inc. pp. 2192-2200 .

Record type: Conference or Workshop Item (Paper)

Abstract

The aim of this research is to create a microphone array on a rigid sphere that could be used for teleconferences and for recording of music with the aim of five-channel loudspeaker surround sound reproduction. Computer simulations have been undertaken, within a MATLAB environment, that test the directivity of circular microphone arrays. The beamformer used in the study is an extension of the "focused beamformer" that attempts to map the distribution of acoustic source strength associated with a given source distribution by changing the Green function vector in accordance with the assumed source position. In the approach used here, it is assumed that multiple sources are present and Tikhonov regularisation is used in order to enable the inversion of the system response. Using an algorithm for the reconstruction of source strength time histories, the improvement in the directivity of the array was achieved by simulating the presence of several sources around the microphone array and then using only the filter corresponding to one of the sources. In that way the directivity is maximum in the source direction and minimum in the directions of the other sources, creating a mainlobe in the main source direction and several dips in response in the directions of the other sources.

This record has no associated files available for download.