An Acoustic comparison of vowel length contrasts in Arabic, Japanese and Thai: durational and spectral data

In our earlier perception study, we observed that familiarity with first language (L1) phonemic length contrasts in Japanese does not transfer optimally into an unknown language, Arabic. We hypothesized that this finding is related to cross-language differences in how vowel length contrasts are phonetically realized. The present study compares acoustic characteristics (i.e., vowel duration, first two formant frequencies (F1, F2)) of the /a/ and /a / vowels that are phonemic in three typologically unrelated languages, i.e., Arabic, Japanese and Thai. We sought to understand the extent to which vowel length contrasts are similar or dissimilar in these languages. Acoustic measurements showed short and long categories were clearly differentiated in duration in all three languages. The effect of length was much more limited for F1 and F2. The finding that the short-to-long ratio did not substantially differ across languages suggests that listeners attend to more than just acoustic vowel duration in making perceptual judgments on short vs. long vowels in a discrimination task.