A Robust Method to Count and Locate Audio Sources in a Multichannel Underdetermined Mixture

We propose a method to count and estimate the mixing directions in an underdetermined multichannel mixture. The approach is based on the hypothesis that in the neighborhood of some time-frequency points, only one source essentially contributes to the mixture: such time-frequency points can provide robust local estimates of the corresponding source direction. At the core of our contribution is a statistical model to exploit a local confidence measure, which detects the time-frequency regions where such robust information is available. A clustering algorithm called DEMIX is proposed to merge the information from all time-frequency regions according to their confidence level. So as to estimate the delays of anechoic mixtures and overcome the intrinsic ambiguities of phase unwrapping as met with DUET, we propose a technique similar to GCC-PHAT that is able to estimate delays that can largely exceed one sample. We propose an extensive experimental study that shows the resulting method is more robust in conditions where all DUET-like comparable methods fail, that is, in particular, a) when time-delays largely exceed one sample and b) when the source directions are very close.