Automated Pause Insertion for Improved Intelligibility Under Reverberation

Speech intelligibility in reverberant environments is reduced because of overlap-masking. Signal modification prior to presentation in such listening environments, e.g., with a public announcement system, can be employed to alleviate this problem. Time-scale modifications are particularly effective in reducing the effect of overlap-masking. A method for introducing linguistically-motivated pauses is proposed in this paper. Given the transcription of a sentence, pause strengths are predicted at word boundaries. Pause duration is obtained by combining the pause strength and the time it takes late reverberation to decay to a level where a target signal-to-late-reverberation ratio criterion is satisfied. Considering a moderate reverberation condition and both binary and continuous pause strengths, a formal listening test was performed. The results show that the proposed methodology offers a significant intelligibility improvement over unmodified speech while continuous pause strengths offer an advantage over binary pause strengths.