A Speech Preprocessing Method Based on Perceptually Optimized Envelope Processing to Increase Intelligibility in Reverberant Environments

Speech intelligibility in public places can be degraded by the environmental noise and reverberation. In this study, a new near-end listening enhancement (NELE) approach is proposed that using a time varying filter jointly enhances the onsets and reduces the overlap masking. For optimization, a some look ahead in the clean speech and prior knowledge of room impulse response (RIR) are required. In this method, by optimizing a defined cost function, the Spectro-Temporal Envelope of a reverb speech is optimized to be as close as possible to that of the clean speech. In this cost function, onsets of speech are optimized with increased weight. This approach is different from overlap-masking ratio (OMR) and speech enhancement (OE) approaches (Grosse, van de Par, 2017, J. Audio Eng. Soc., Vol. 65(1/2), pp. 31-41) that only considers previous frames in each time slot for determining the time variant filtering. The SRT measurements shows that the new optimization framework in average enhances the speech intelligibility up to 2 dB more that OE.