Spherical beam-forming and music methods for the estimation of location and strength of spherical sound sources

Abstract This paper shows the effect of spherical wave fronts on conventional noise source identification methods which assume a planar wave front. The effects of the array parameters, namely, the distance between the adjacent microphones, the aperture size of a microphone array, and the bearing angle of noise source on the estimation errors have been studied in conditions where the noise field can be considered as the superposition of planar wave fronts. Following these observations, spherical beam-forming and spherical MUSIC methods which incorporate the spherical wave fronts have been formulated and analysed. The validity of these methods in identifying the location and strength of the noise source has been tested by numerical simulations in terms of the various array parameters and also by experiments conducted in an anechoic room. The application and possible extension of the suggested methods for the identification of multiple spherical sources with finite frequency bands are described.