Speech enhancement of instantaneous amplitude and phase for applications in noisy reverberant environments

- We introduced a restoration scheme for instantaneous amplitude and phase in noisy reverberant environments.
- We dealt with the summation of additive noise and late reverberant speech in the Kalman filter and removed the early reflection effect by CMN.
- Objective and subjective experiments revealed that the proposed method can improve both quality and intelligibility of speech in noisy reverberant environments.
- The results of ASR experiments showed that the proposed method outperforms the conventional methods to work well in noisy reverberant environments.

We previously proved that restoring the instantaneous amplitude as well as instantaneous phase on the output from Gammatone filterbank plays a significant role in speech enhancement. However, dereverberation is still a challenge since the previously proposed scheme can only work in noisy environments. In this paper, we extend our previously proposed scheme to general speech enhancement for removing both the effects of noise and reverberation by restoring instantaneous amplitude and phase simultaneously. Objective and subjective experiments were conducted under various noisy reverberant conditions to evaluate the effectiveness of the extension of the proposed scheme. The signal to error ratio (SER), correlation, PESQ, and SNR loss were used in objective evaluations. The normalized mean preference score and correctness in modified rhyme test (MRT) were used in subjective evaluations. We also tested how effective our proposed scheme is as a front-end for an automatic speech recognition (ASR) system in realistic noisy reverberant environments. The results of all evaluations revealed that the proposed scheme could effectively improve quality and intelligibility of speech signals under noisy reverberant conditions.