An Iterative Approach to Source Counting and Localization Using Two Distant Microphones

We propose a time difference of arrival (TDOA) estimation framework based on time-frequency inter-channel phase difference (IPD) to count and localize multiple acoustic sources in a reverberant environment using two distant microphones. The time-frequency (T-F) processing enables exploitation of the nonstationarity and sparsity of audio signals, increasing robustness to multiple sources and ambient noise. For inter-channel phase difference estimation, we use a cost function, which is equivalent to the generalized cross correlation with phase transform (GCC) algorithm and which is robust to spatial aliasing caused by large inter-microphone distances. To estimate the number of sources, we further propose an iterative contribution removal (ICR) algorithm to count and locate the sources using the peaks of the GCC function. In each iteration, we first use IPD to calculate the GCC function, whose highest peak is detected as the location of a sound source; then we detect the T-F bins that are associated with this source and remove them from the IPD set. The proposed ICR algorithm successfully solves the GCC peak ambiguities between multiple sources and multiple reverberant paths.