Underwater soundfield visualisation using directionally constrained acoustic parameters

This paper presents an underwater soundfield visualisation method for passive-sonar applications employing circular hydrophone arrays. The method operates by segregating the space by means of beamforming into angular sectors scanning the whole horizontal plane and then computing acoustic parameters within each sector. The information from these directionally constrained parameters is fused in order to produce spatial spectra which depict the distribution of acoustic energy over bearing. The evaluation is performed on simulated data of circular hydrophone arrays mounted on rigid cylindrical baffles. Comparisons against baseline methods of similar computational complexity suggest that, for moderate to high signal-to-noise ratio levels, the proposed method offers improved performance in terms of background noise suppression, angular resolution, and direction-of-arrival estimation accuracy. Additionally, it is demonstrated that, with the appropriate choice of sector pattern, the proposed method can, at least in some cases, achieve superior performance to the baseline methods in the presence of interferers even at low signal-to-interference ratio levels. Last, the sector-based parameter diffuseness, which is directly related to the direct-to-diffuse ratio, may be used both as a weight function to further attenuate the background noise level and as a confidence measure of the estimation accuracy.