An iterative approach to sound source localization based on spherical beamforming

Precise and efficient localization of sound sources is essential in many applications. Traditionally, methods that use beamforming tend to scan the entire space with fixed level of precision. Although effective, this approach is inefficient when searching for a single source. In this paper we propose an iterative algorithm for localizing a single sound source utilizing signals from a 4th order ambisonic microphone array. Two beamformers were implemented: one based on signals in A-format, incorporating delay-and-sum method, commonly used for sound source localization, and the second one based on B-format, operating in the spherical harmonic domain. By utilizing an iterative algorithm, we have significantly decreased the number of points to be evaluated to localize the sound source. For the delay-and-sum beamformer, the best outcome was obtained by using all 32 channels in every iteration. For the spherical-harmonics-based beamformer, the best strategy was to use first-order harmonics in the initial iteration and fourth-order harmonics in subsequent iterations.