Recurrent Neural Networks for Cochannel Speech Separation in Reverberant Environments

Speech separation is a fundamental problem in speech and signal processing. A particular challenge is monaural separation of cochannel speech, or a two-talker mixture, in a reverberant environment. In this paper, we study recurrent neural networks (RNNs) with long short-term memory (LSTM) in separating and enhancing speech signals in reverberant cochannel mixtures. Our investigation shows that RNNs are effective in separating reverberant speech signals. In addition, RNNs significantly outperform deep feedforward networks based on objective speech intelligibility and quality measures. We also find that the best performance is achieved when the ideal ratio mask (IRM) is used as the training target in comparison with alternative training targets. While trained using reverberant signals generated by simulated room impulse responses (RIRs), our model generalizes well to conditions where the signals are generated by recorded RIRs.