This paper details a software implementation of an acoustic camera, which utilises a spherical microphone array and a spherical camera. The software builds on the Cross Pattern Coherence (CroPaC) spatial filter, which has been shown to be effective in reverberant and noisy sound field conditions. It is based on determining the cross spectrum between two coincident beamformers. The technique is exploited in this work to capture and analyse sound scenes by estimating a probability-like parameter of sounds appearing at specific locations. Current techniques that utilise conventional beamformers perform poorly in reverberant and noisy conditions, due to the side-lobes of the beams used for the powermap. In this work we propose an additional algorithm to suppress side-lobes based on the product of multiple CroPaC beams. A Virtual Studio Technology (VST) plug-in has been developed for both the transformation of the time-domain microphone signals into the spherical harmonic domain and the main acoustic camera software; both of which can be downloaded from the companion web-page.

Download