客語兒向語與成人語單、雙元音聲學比較研究 (AN ACOUSTIC COMPARISON OF MONOPHTHONGS AND DIPHTHONGS BETWEEN HAKKA INFANT-DI-RECTED AND ADULT-DIRECTED SPEECH)
This study acoustically analyzed monophthongs and diphthongs in Hakka infant-directed speech (IDS) and adult-directed speech (ADS). Ten mother-infant dyads joined this study. The speech stimuli included eleven commonly-used disyllabic phrases, the first syllables of which were the target words. This study selected three clear tokens from each disyllabic phrase, and used PRAAT to measure the values of the first and second formant of all samples, normalized formant values into Bark values, and used Bark values to draw the vowel space of monophthongs and the trajectories of diphthongs, and to count vowel-related acoustic correlates. The re-sults were stated as follows. First, monophthongs and diphthongs in IDS became longer than those in ADS. Second, as compared with ADS, IDS displayed a down-ward-moving vowel space, a slightly shrinking vowel space area, and shorter acoustic vowel distances. Third, as compared with ADS, IDS showed longer dura-tion and longer acoustic distances in diphthongs. Fourth, the similar onset-rime percentages in both IDS and ADS are helpful for infants to create the concepts of syllables and cultivate the ability of phonological awareness later.