Blind and Spatially-Regularized Online Joint Optimization of Source Separation, Dereverberation, and Noise Reduction

This paper proposes a computationally efficient joint optimization algorithm that performs online source separation, dereverberation, and noise reduction based on blind and spatially-regularized processing. When applying such online Blind Source Separation (BSS) as online Independent Vector Extraction (IVE) to a speech application, we must focus on the trade-off between the algorithmic delay and separation accuracy, both of which depend on the analysis frame length. In addition, to separate the sources with specified source permutation, researchers introduced spatial regularization based on the Directions-of-Arrival (DOAs) of the sources into IVE. However, the scale ambiguity of IVE often makes the spatial regularization work inappropriately. To solve these problems, we first propose a blind online joint optimization algorithm of IVE and weighted prediction error dereverberation (WPE). This online algorithm can achieve accurate separation even using short analysis frames because reverberation can be reduced using WPE. We then extend the online joint optimization with robust spatial regularization. We reveal that regularizing the scale of the separated signals is very effective in making the DOA-based spatial regularization work reliably. Our experiments confirm that our blind online joint optimization algorithm can significantly improve the separation accuracy with an algorithmic delay of 8 ms. In addition, we confirm that the proposed spatially-regularized online joint optimization algorithm reduces the rate of the source permutation error to zero percent.