Benefitting from the three-dimensional symmetry, spherical array plays an important role in next-generation multimedia communication, sound field analysis and reconstruction. As a result, it becomes a new research area of interest in the last decade. Several researchers contributed to beamforming of spherical array. However, spherical harmonics is computationally complex. Fortunately, there are some efficient fast computing algorithms for the spherical harmonic transform.

LI Xuan, YAN Shefeng, MA Xiaochuan and HOU Chaohuan of Institute of Acoustics, Chinese Academy of Sciences emphasize the direction-of-arrival (DOA) estimation of the spherical arrays and proposed MUSIC algorithm in spherical space, named as SH-MUSIC,based on the orthogonality of the sensors’ location.

On account of the transformation matrix's orthogonality, spherical harmonics transformation is suggested to be operated firstly in other improved MUSIC algorithms without rejection, and it is demonstrated in beamspace MUSIC. In addition, owing to the tiny error between the steering vectors and the spherical harmonics with high order, sphere array data models including open sphere and rigid sphere are constructed. Simulation proves SH-MUSIC to be effective. Moreover, experimental data from a rigid sphere microphone array is dealt with by SH-MUSIC and the DOAs are estimated accurately.

This research result was published on the recently issued Journal of Applied Acoustics (Vol.72,Issue 9, Sep.2011, pp: 646-652)