Unified denoising and dereverberation method used in restoration of MTF-based power envelope

Recent methods of speech enhancement have been proposed to suppress the effects of background noise and reverberation. The effect of background noise in these methods is regarded as additive and that of reverberation is convolutive. Therefore, methods of reducing noise and dereverberation have been applied separately in tandem. We previously unified the effects of noise and reverberation in the modulation transfer function (MTF) concept and we proposed an approach to simultaneously removing the effects of noise and reverberation. This paper further verifies our proposed approach, mathematically and quantitatively. In addition, we generalized the model to four types of real application scenarios, which corresponded to far and near field conditions under noisy reverberant conditions, based on mathematical analysis. We carried out 12,000 simulations for each according to the four application scenarios for denoising and dereverberating noisy reverberant speech, and objectively evaluated the proposed approach. The experimental results revealed that the proposed approach worked well in simultaneously denoising and dereverberating noisy reverberant speech.