Effects of excitation spread on the intelligibility of Mandarin speech in cochlear implant simulations

Noisy listening conditions remain challenging for most cochlear implant patients. The present study simulated the effects of decay rates of excitation spread in cochlear implants on the intelligibility of Mandarin speech in noise. Mandarin sentence and tone stimuli were processed by noise-vocoder, and presented to normal-hearing listeners for identification. The decay rates of excitation spread were simulated by varying the slopes of synthesis filters in noise-vocoder. Experimental results showed that significant benefit for Mandarin sentence recognition in noise was observed with narrower type of excitation. The performance of Mandarin tone identification was relatively robust to the influence of excitation spread. The results in the present study suggest that reducing the decay rates of excitation spread may potentially improve the speech perception in noise for cochlear implants in the future.