Audiovisual integration in fricative production and perception by nonnative speakers

Lip rounding enhances the acoustic contrast between /s/ and /ʃ/ in English. For speakers of languages without this phonemic distinction, to what degree does lip rounding affect the production and perception of these fricatives? Is visual awareness of lip rounding associated with audiovisual integration commonly observed in the McGurk effect? How does this performance develop as a function of exposure to English? Fourteen learners of English participated in three tasks. First, participants read a list of /s/-/ʃ/ minimal pairs. The spectral center of gravity was measured to examine learners’ production of the contrast. Second, participants watched/listened to the same words produced by a native English speaker in four presentation formats: audio only, audiovisual-congruent, audiovisual-incongruent (e.g., an audio /s/ paired with a visual /ʃ/), and visual only. Finally, participants listened to four stop-vowel syllables paired with either congruent or incongruent videos. Two experimental sessions were conduc...