Ultrasound study for patterns of tongue movement in diphthongs, triphthongs, and vowel sequences in Korean, Japanese, and Mandarin

Diphthongs have formant transitions sensitive to speaking rate, stress, vowel quality, and language ability. Tongue movement typically shows a functional “pivot” where the palate to tongue distance is almost constant; some combinations result in an “arch,” with only part of the tongue moving [Iskarous, J. Phon. 33, 363-381, 2005]. Here, ultrasound images of the tongue in Korean, Japanese, and Mandarin diphthongs and triphthongs (Mandarin) (vowel sequences in Korean and Japanese) were analyzed. Five repetitions of 6 nonwords were presented in Hangul, Hiragana or both Pinyin and a character for a word with the same vowel on tone 1. Diphthongs were [ai, ei, au] and triphthongs/sequence of three vowels were [iau, ieu, and uai]. All the ultrasound image frames for the target vowels were traced and superimposed. Preliminary results indicate that most vowel quality pairs resulted in a pivot pattern, with some arch patterns as well. Even in Mandarin triphthongs, there were generally two pivots, even though phonol...