Beamforming method: suppression of spatial aliasing using moving arrays

In the scientific and industrial community a growing interest is nowadays devoted to sound source localization techniques. Among all the existing methods, the use of the beamforming algorithm in sound source localization problems is increasing, thanks to its many advantages if compared to the other available methods (Nearfield Acoustic Holography and Helmholtz Equation Least Square Method). The beamforming limits are well known and deeply investigated in literature and the study of possible solutions to overcome these limitations is a key point. The present paper deals with the spatial aliasing problem and proposes an innovative approach to improve the method performances. The spatial aliasing phenomenon causes the appearance of “ghost sources” in the reconstructed images. An innovative solution based on the use of moving microphone arrays is here proposed. The array motion, multiplying the measurement points, allows to reduce the aliasing errors. This paper presents the theoretical background of the innovative method and the results obtained with numerical simulations, in comparison with the traditional “Delay & Sum” method. The influence of some parameters, such as the array speed, and the geometry are investigated and a first experimental validation is given.