Effects of visual speech information on native listener judgments of L2 consonant intelligibility

The present study examines how visual information in nonnative phonemes affects perceptual accuracy of second language (L2) speech production. Native Canadian English listeners perceived three English phonemic contrasts produced by native speakers of Japanese as well as native speakers of Canadian English as controls, under audiovisual (AV), audioonly (AO), and visual-only (VO) conditions. The phonemes include /v, !, l, "/, which are not existent in Japanese (L2 phonemes) as well as /b, s/ that are shared in both Japanese and English consonant inventories. The results showed that the English listeners perceived the Japanese productions of the phonemes /b, v, s, !/ as significantly more intelligible when presented with the AV condition compared to the AO condition, indicating facilitative effects of visual speech information on their perceptual accuracy of nonnative production. However, the Japanese production of /"/ was perceived as less intelligible in the AV condition compared to the AO condition, indicating that nonnative speakers’ incorrect articulatory configurations may decrease the degree of intelligibility. These results suggest that listener judgments of L2 productions may be either positively or negatively affected by additional visual speech information.