Cross-language perception of the Japanese singleton/geminate contrasts: comparison of Vietnamese speakers with and without Japanese language experience

We examined the perception of Japanese consonant length by three groups of Vietnamese speakers and a group of 10 Japanese speakers. Two of the Vietnamese groups consisted of learners of Japanese with one group participating in Vietnam (n = 17) and the other in Japan (n = 13). The third Vietnamese group consisted of 12 participants inexperienced in Japanese. Unlike Japanese, consonant length is non-contrastive in Vietnamese. Thus, we were interested in how different experience with Japanese may influence the perception of difficult Japanese contrasts. The overall mean discriminability in d-prime was 1.0, 1.9, 3.1 and 4.5 for the non-learner group, the learner group in Vietnam, the learner group in Japan and the native Japanese group, respectively. A clear difference between the two learner groups demonstrates learnability of Japanese consonant length for grownups. At the same time, the qualitative difference between the advanced learners and native Japanese speakers suggests genuine and persistent difficulty of Japanese consonant length. By providing additional empirical data beyond the segmental level, this study helps us to better evaluate the extent to which current theories of second language (L2) speech learning account for the acquisition of a wide range of L2 sounds by speakers from diverse first language backgrounds.