This article addresses the multi-channel linear prediction (MCLP)-based speech dereverberation problem by jointly considering the sparsity and low-rank priors of speech spectrograms. We utilize the complex generalized Gaussian (CGG) distribution as the source model and the generalized nonnegative matrix factorization (NMF) as the spectral model. The difference between the presented model and existing ones for MCLP is twofold. First, we adopt the CGG distribution with a time-frequency-variant scale parameter instead of that with a time-frequency-invariant scale parameter. Second, the time-frequency-varying scale parameter is approximated by NMF in a low-rank manner. Based on the maximum-likelihood criterion, speech dereverberation is formulated as an optimization problem that minimizes the prediction error weighted by the reciprocal of sparse and low-rank parameters. A convergence-guaranteed algorithm is derived to estimate the parameters using the majorization-minimization technology. The WPE, NMF-based WPE and CGG-based WPE can be treated as special cases of the proposed method with different shape and domain parameters. As a byproduct, the proposed method provides a simple and elegant way to derive the CGG-based WPE algorithm. A series of experiments show the superiority of the proposed method over WPE, NMF-based WPE and CGG-based WPE methods.

Most multichannel blind source separation (BSS) approaches rely on a spatial model to encode the transfer functions from sources to microphones and a source model to encode the source power spectral density. The rank-1 spatial model has been widely exploited in independent component analysis (ICA), independent vector analysis (IVA), and independent low-rank matrix analysis (ILRMA). The full-rank spatial model is also considered in many BSS approaches, such as full-rank spatial covariance matrix analysis (FCA), multichannel nonnegative matrix factorization (MNMF), and FastMNMF, which can improve the separation performance in the case of long reverberation times. This paper proposes a new MNMF framework based on the convolutive transfer function (CTF) for overdetermined BSS. The time-domain convolutive mixture model is approximated by a frequency-wise convolutive mixture model instead of the widely adopted frequency-wise instantaneous mixture model. The iterative projection algorithm is adopted to estimate the demixing matrix, and the multiplicative update rule is employed to estimate nonnegative matrix factorization (NMF) parameters. Finally, the source image is reconstructed using a multichannel Wiener filter. The advantages of the proposed method are twofold. First, the CTF approximation enables us to use a short window to represent long impulse responses. Second, the full-rank spatial model can be derived based on the CTF approximation and slowly time-variant source variances, and close relationships between the proposed method and ILRMA, FCA, MNMF and FastMNMF are revealed. Extensive experiments show that the proposed algorithm achieves a higher separation performance than ILRMA and FastMNMF in reverberant environments.