Abstract: Beamforming with a spherical array is an effective 3D sound source identification technology. The existed spherical harmonics beamforming can locate sound sources accurately, but it fails to quantify the acoustical contributions of sound sources, and that its results are affected by the focus distance seriously. Usually, pressure contribution each sound source makes to the array centre is an effective basis in ranking sound sources. In order to calculate the pressure contribution, an extension method of spherical harmonics beamforming is proposed and the influence rule of focus distance on the accuracy of the method is explored. Simulations of the given sound sources show that the method can not only locate sound sources but also calculate sound pressure contributions accurately. Concretely, the maximum error is less than 0.5 dB up to 3 000 Hz and less than 1.5 dB in 3 000-6 000 Hz. In addition, the accuracy of the method is hardly affected by the focus distance. Finally, experiment with loudspeaker sound sources validates correctness of the simulations and effectiveness of the method in practical applications.

Key words: beamforming, sound pressure contribution, sound source identification, spherical array