Coherent spectral estimation for a robust solution of the permutation problem

In this paper, we propose a new method based on a coherent source spectral estimation for solving the permutation problem of frequency-domain blind source separation (BSS). It combines the robustness of the State Coherence Transform (SCT) to recursively estimate a smooth phase spectrum associated with each source and the precision of the inter-frequency correlation to solve for a correct permutation. Namely, the TDOAs estimated by the SCT are used to constrain the permutation correction process in order to force the resulting filters to be coherent across frequency. This intrinsic interconnection between the TDOA information and the spectral correlation makes the new approach robust even when the signal is short in duration and spatial aliasing is substantial. Experimental results show that the proposed method is able to drastically reduce the number of permutation errors for three sources recorded in a short time block using microphones with large spacing.