The role of vowel duration cue in L1: Effects on L2 learners' identification of phonological vowel length in Japanese

This study investigated the effects of learners’ L1 on their identification of Japanese phonological vowel length at three speaking rates. Native listeners of Japanese (NJ) and learners of Japanese with L1 backgrounds in Finnish (NFin), American English (NE), Russian (NR), and French (NFr) participated in the study. The results showed that the proportion of “long” responses increased as a function of vowel duration for all groups. Meanwhile, only NJ and NFin shifted the category boundary location according to speaking rate, which occurred at a shorter duration for a faster speaking rate. In addition, NFr’s boundary width was significantly greater than NJ’s and NFin’s. These results suggest that L2 learners can access vowel duration as a cue regardless of their L1, but only those whose L1 uses vowel duration as a cue for phonological vowel length can shift the category boundary appropriately and identify L2 vowel length sharply as NJ do.