Design and orthonormality analysis of trijunctional spherical microphone array

Spherical microphone arrays have been widely studied for sound recording, beamforming, and sound-field analysis due to the advantage of its spherical symmetry. A trijunctional sampling scheme for spherical microphone array is proposed in this paper. All its samples are on the junctions of three great circles which are respectively chosen from three different series with mutually orthogonal rotation axes. So the trijunctional sampling scheme holds a rotational symmetry with respect to each rotation axis, which makes it easy to obtain the coordinates and the weights of samples. Besides, an analysis of spherical harmonics orthonormality indicates that the array redundancy of trijunctional sampling scheme is much lower than that of equiangular and Gaussian sampling schemes.