On the role of visual rate information in phonetic perception

Abstract

It is well established that listeners process segmentally relevant properties of the speech signal in relation to the rate at which the speech was produced. We investigated whether the critical rate information for this effect is limited to the auditory modality or, alternatively, whether visual rate information provided by the talker's face also plays a role. Audio-visual syllables were created by pairing tokens from a moderate-rate, auditory /bi/-/pi/ series with visual tokens of /bi/ or /pi/ produced at a faster or slower rate of speech; these visual tokens provided information about speaking rate, but could not themselves be identified correctly as /bi/ or /pi/. Each audiovisual pairing produced the phenomenal experience of a single, unified syllable, /bi/ or /pi/, spoken at a single rate of speech. The change in visual rate information across the syllables influenced the judged rate of the audio-visual syllables and, more importantly, affected their identification as /bi/ or /pi/. These results indicate that visual information about speaking rate is relevant to the perception of voicing and, more generally, suggest that the mechanisms underlying rate-dependent speech processing have a bimodal (or amodal) component. © 1985 Psychonomic Society, Inc.