Effect of acoustic fine structure cues on the recognition of auditory-only and audiovisual speech.

This study addressed the hypothesis that an improvement in speech recognition due to combined envelope and fine structure cues is greater in the audiovisual than the auditory modality. Normal hearing listeners were presented with envelope vocoded speech in combination with low-pass filtered speech. The benefit of adding acoustic low-frequency fine structure to acoustic envelope cues was significantly greater for audiovisual than for auditory-only speech. It is suggested that this is due to complementary information of the different acoustic and visual cues. The results have potential implications for the assessment of bimodal cochlear implant fittings or electroacoustic stimulation.