Effects of phonetic context on audio-visual intelligibility of French.
Bimodal perception leads to better speech understanding than auditory perception alone. We evaluated the overall benefit of lip-reading on natural utterances of French produced by a single speaker. Eighteen French subjects with good audition and vision were administered a closed set identification test of VCVCV nonsense words consisting of three vowels [i, a, y] and six consonants [b, v, z, 3, R, l]. Stimuli were presented under both auditory and audio-visual conditions with white noise added at various signal-to-noise ratios. Identification scores were higher in the bimodal condition than in the auditory-alone condition, especially in situations where acoustic information was reduced. The auditory and audio-visual intelligibility of the three vowels [i, a, y] averaged over the six consonantal contexts was evaluated as well. Two different hierarchies of intelligibility were found. Auditorily, [a] was most intelligible, followed by [i] and then by [y]; whereas visually [y] was most intelligible, followed by [a] and [i]. We also quantified the contextual effects of the three vowels on the auditory and audio-visual intelligibility of the consonants. Both the auditory and the audio-visual intelligibility of surrounding consonants was highest in the [a] context, followed by the [i] context and lastly the [y] context.
Benoît
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Institut de la Communication Parlée, URA CNRS no. 368, INPG-ENSERG/Université Stendhal, Grenoble, France.
Mohamadi
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Kandel
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D000328:Adult; D001307:Auditory Perception; D003463:Cues; D005069:Evaluation Studies as Topic; D005149:Facial Expression; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D010470:Perceptual Masking; D010700:Phonetics; D013061:Speech Acoustics; D013065:Speech Intelligibility; D014796:Visual Perception