Impact of Japanese L1 Rhythm on English L2 Speech

The study aimed to examine whether L1 speech rhythm affects L2 speech by assessing how the speech rhythm of Japanese L2 English speakers differed from native speakers. We chose Japanese and English because they differ markedly in the phonological properties that likely contribute to speech rhythm. Speech rhythm was measured by the variability of vowel and consonant intervals using rate-normalized rhythm metrics (VarcoV and VarcoC; nPVI-V and nPVI-C) and %V. The study utilized recordings of spoken sentences in English by 10 native Australian English speakers; and in English and also in Japanese by 10 native Japanese speakers (who had limited experience in speaking English). Experiment 1 compared the rhythm of L1 English (by measuring 1,750 vowels and 3,093 consonants from 20 sentences) and L1 Japanese (1,923 vowels and 2,097 consonants from 10 sentences). The results showed that for all measures, Japanese had reduced durational variability in both consonant and vowel intervals compared with English. In Experiment 2, we examined the rhythm characteristics of L1 and L2 English using 40 sentences (including the 20 in Experiment 1). The results showed that vowel and consonant intervals were less variable in L2 (Japanese English) than in L1 (Australian English) speech, mirroring the results of Experiment 1. Overall, the results are consistent with the proposal that L1 (Japanese) speech rhythm influenced L2 (English) speech.