Permutation-free convolutive blind source separation via full-band clustering based on frequency-independent source presence priors
Nobutaka Ito, Shoko Araki, Tomohiro Nakatani · 2013
We propose permutation-free frequency-domain blind source separation (BSS) via full-band clustering of the time-frequency (T-F) components based on time-varying signal presence priors. Frequency-domain methods of BSS usually process each frequency bin separately, and therefore necessitate the subsequent alignment of the permutation ambiguity that arises between frequency bins. In contrast, the proposed method simultaneously processes all frequency bins by using a mixture model with time-varying, frequency-independent mixture weights. We propose to assume non-sparse priors on the mixture weights to prevent the degradation of source separation performance by the time-varying mixture weights. We propose a customized expectation-maximization (EM) algorithm for the maximum a posteriori (MAP) estimation of the model parameters, to which we introduce a novel technique to avoid convergence to local maxima. For audio source separation, we use the normalized observation vector as the feature vector, and theWatson mixture model (WMM) as the mixture model. Evaluations confirm that the proposed permutation-free BSS results in source separation performance comparable to the state-of-the-art clustering-based BSS composed of bin-wise clustering and permutation alignment.