A unified DNN approach to speaker-dependent simultaneous speech enhancement and speech separation in low SNR environments

We propose a unified speech enhancement framework to jointly handle both background noise and interfering speech in a speaker-dependent scenario based on deep neural networks (DNNs). We first explore speaker-dependent speech enhancement that can significantly improve system performance over speaker-independent systems. Next, we consider interfering speech as one noise type, thus a speaker-dependent DNN system can be adopted for both speech enhancement and separation. Experimental results demonstrate that the proposed unified system can achieve comparable performances to specific systems where only noise or speech interference is present. Furthermore, much better results can be obtained over individual enhancement or separation systems in mixed background noise and interfering speech scenarios. The training data for the two specific tasks are also found to be complementary. Finally, an ensemble learning-based framework is employed to further improve the system performance in low signal-to-noise ratio (SNR) environments. A voice activity detection (VAD) DNN and an ideal ratio mask (IRM) DNN are investigated to provide prior information to integrate two sub-modules at frame level and time-frequency level, respectively. The results demonstrate the effectiveness of the ensemble method in low SNR environments.