Local Gaussian model with source-set constraints in audio source separation

To improve the performance of blind audio source separation of convolutive mixtures, the local Gaussian model (LGM) having full rank covariance matrices proposed by Duong et al. is extended. The previous model basically assumes that all sources contribute to each time-frequency slot, which may fail to capture the characteristic of signals with many intermittent silent periods. A constraint on source sets that contribute to each time-frequency slot is therefore explicitly introduced. This approach can be regarded as a relaxation of the sparsity constraint in the conventional time-frequency mask. The proposed model is jointly optimized among the original local Gaussian model parameters, the relaxed version of the time-frequency mask, and a permutation alignment, leading to a robust permutation-free algorithm. We also present a novel multi-channel Wiener filter weighted by a relaxed version of the time-frequency mask. Experimental results over noisy speech signals show that the proposed model is effective compared with the original local Gaussian model and is comparable to its extension, the multi-channel nonnegative matrix factorization.