Mispronunciation of Japanese singleton and geminate stops by Korean and Taiwanese Mandarin speakers

Non-native Japanese speakers often mispronounce Japanese singleton and geminate stops. Previous studies have pointed out that non-native speakers' mispronunciations are caused by an inadequate closure duration, which is the primary acoustic cue to distinguish singleton and geminate stops. However, the durations of preceding and following segments of the closure have not been fully investigated. In this study, the durations of the closure and the preceding and following consonant-vowel segments were analyzed to clarify the characteristics of Japanese singleton and geminate stops mispronounced by Korean and Taiwanese Mandarin speakers. The results revealed that the non-native speakers pronounced singleton stops with a longer closure and a shorter preceding consonant-vowel segment than the native Japanese speakers. In contrast, they pronounced geminate stops with a shorter closure and a longer following consonant-vowel segment than the native Japanese speakers. These results indicate that non-native speakers' mispronunciations of Japanese singleton and geminate stops are caused by both inadequate closure duration and anteroposterior segment durations. It is likely that the reason for the mispronunciation is the difference in the rhythmic unit between Japanese and the first languages of the non-native speakers.