苗栗四縣客家話兒向語與成人語陽平調與陰平變調的聲學比較研究

An Acoustic Comparison of the Yangping Tone and the Yinping Tone Sandhi of Infant Directed Speech and Adult Directed Speech in Miaoli Sixian Hakka

兒向語與成人語的聲調差異已獲許多研究證實，但連讀變調在其間的語音表現卻未受關注。據此，本研究將以苗栗四縣客家話的陰平變調為例，探討其在兩種語體中的語音表現。本研究的參與者為8對母嬰配對，嬰兒年齡介於6至8個月。發音字表包括21個以C1V1C2V(C)為結構的雙音節詞組，C1與C2為無聲輔音，V1為[i, a, u]三個頂點，並為目標聲調所在。兒向語與成人語皆在受訪者家中錄製，且均來自母親與其嬰兒及研究者的自然言語互動。分析顯示，兒向語裡的各個本調均呈現調形誇大、調值提升、調域變寬、聲調升降急遽。然而，有別於陽平本調在兩種語體裡的語音差異，陰平變調的所有基頻相關參數在兩種語體的表現不存在顯著差異。最後，本研究闡釋為何兩種語體的陰平變調未呈現顯著差異，並探討兒童習得變調較晚之因。

A great body of research of infant-directed speech(IDS) in tonal languages has fousedon comparing the realizations of citation tones in IDS and adult-directed speech (ADS). Little attention is directed to the comparisons of sandhi tones between both registers. Thus, this study, based on Taiwan Sixian Hakka (TSH), targeted to investigate how the Yinping tone (T1)sandhi is realized in Hakka IDS, and compared it with the Yangping citation tone (T2) in ADS and IDS. Eight mother-infant dyads aging from 6 to 8 months joined this study. Speech stimuli contained 21 disyllabic phrases shaped by C1V1C2V(C), where C1and C2were voiceless consonants and V1 was one of the corner vowels [i, a, u] and carried the target citation and sandhi tones. Mothers vocally interacted with their infants and the researcher naturally at homes, and these speeches were recorded as IDS and ADS respectively. For each register, the first three clear tokens of all target tones were segmented for acoustic analysis by PRAAT. Results showed that IDS citation tones were more hyperarticulated than ADS ones in all F0-related correlates. However, unlike citation T2, sandhi T2s exhibited a phonetic realization similar in both registers, and similar to the ADS citation T2 in all F0-related correlates. The results can interpret why no significant difference occurs in the acoustic correlates in both registers, and explain children’s late acquisition of sandhi tones.