Visual-auditory integration and vocalic effects on fricative perception.

Abstract

This study investigates the effect of visual presentation of four syllables ([sa], [sha], [su], [shu]) on perception of a fricative noise continuum. The visual stimuli were taken from videotapes of a speaker uttering the four syllables. The nine-step noise continuum ranged from [s] to [sh], and when followed by the acoustic vocalic portions taken from natural utterances of [sa], etc., replicated Mann and Repp’s (1980) findings about the context effects of vowel lip rounding and consonant place of articulation on fricative perception. To determine if similar context effects would occur when the vocalic information was specified visually rather than auditorily, stimuli from the noise continuum were dubbed in place of the natural utterances on the video tapes and subjects identified the visual-auditory hybrids by naming each syllable aloud. The results showed a significant lip rounding effect on perception of ‘‘s’’ vs ‘‘sh’’ indicating that listeners’ compensation for the decrease in frication noise frequency that is caused by anticipatory lip rounding takes place whether the lip rounding is perceived visually or auditorily. The effect of consonant place of articulation was less consistent.