Combined effects of amplitude compression and reverberation on speech modulations
Nirmal Kumar Srinivasan, Frederick J. Gallun, Paul N. Reinhart, Pamela E. Souza · The Journal of the Acoustical Society of America · 2014
It is well documented that reverberation in listening environments is common, and that reverberation reduces speech intelligibility for hearing impaired listeners. it has been proposed that multichannel wide-dynamic range compression (mWDRC) in hearing aids can overcome this difficulty. However, the combined effect of reverberation and mWDRC on speech intelligibility has not been examined quantitatively. In this study, 16 nonsense syllables (/aCa/ format) recorded in a double-walled sound booth were distorted using virtual acoustic methods to simulate eight reverberant listening environments. Each signal was then run through a hearing-aid simulation which applied four-channel WDRC similar to that which might be applied in a wearable aid. Compression release time was varied between 12 and 1500 ms. Consonant confusion matrices were predicted analytically by comparing the similarity in the modulation spectra for clean speech and compressed reverberant speech. Results of this acoustical analysis suggest that the consonant error patterns would be strongly influenced by the combination of compression and reverberation times. If confirmed behaviorally and extended to wearable hearing aids, this outcome could be used to determine the optimum compression time for improved speech intelligibility in reverberant environments. [Work supported by NIH R01 DC60014 and R01 DC011828.]