Three-dimensional sound source diagnostic using a spherical microphone array from multiple capture positions

Most sound source diagnosis systems based on acoustic images are spatially stationary and unable to combine information from multiple capture positions, resulting in unreliable and partial diagnostics. In this paper it is proposed, developed and validated a measurement method based on a mobile spherical microphone array that generates acoustic images using beamforming from multiple capture positions, called Acoustic Imaging Structure From Motion (AISFM). The tridimensional localization, magnitude and directivity of multiple sound sources may be recovered with or without knowledge of the capture positions. An automatic and unsupervised acoustic image processing algorithm is deployed to facilitate the measurement workflow. An acoustic image correspondence problem is solved in order to eliminate false -positives and false-negatives from the diagnostic and render the AISFM feasible. Sound sources localization uncertainties estimates related to the sources' magnitude, directivity and extension projected on the acoustic images are used in order to improve the diagnosis. The method and its effectiveness are experimentally validated with a measurement setup comprising five simultaneous sound sources on an anechoic environment.