客語兒向語中聲調與元音的互動

Interaction between Tones and Vowels in Hakka Infant-Directed Speech

「兒向語」是一種成人對嬰兒說話時所採用的特殊語體，也是兒童語言習得早期最重要的語言輸入。兒向語中聲調與元音的語音表現已為大量文獻所關注，但是兩者之間的互動卻鮮少在兒向語研究中被論及，因此本研究將透過客語企圖對兒向語裡聲調與元音的互動進行分析。本研究採用18個雙音節詞為研究字詞，其中第一個音節為目標音節（6個聲調+3個元音）。本研究收集了14位說客語的母親的成人語與兒向語語音樣本，並利用PRAAT進行基頻與共振峰分析。本研究首先對兩種語體中聲調與元音的表現差異進行個別討論，接著討論兒向語中聲調與元音的互動關係。研究發現如下：第一，就聲調而言，與成人語相比，兒向語聲調在基頻均值、基頻全距、基頻輪廓及基頻斜率都有顯著的擴張，充分體現兒向語「語音強化」的特點。第二，就元音而言，與成人語相比，兒向語裡的元音空間格局下降，元音聲學距離縮短，元音空間面積也小幅縮小，這些與文獻上的記錄不同，只有元音時長的延長是顯著的。本研究認為這與聲調的影響有關。第三，元音的內在音高差異對兒向語裡的聲調影響並不明顯。第四，聲調差異對兒向語裡的元音空間格局及元音空間面積都存有明確的影響，而且影響元音的聲調特徵及作用力大小呈現固定的趨勢，即：舒／入＞高／非高＞平／曲。最後，本研究利用研究發現來闡釋兒向語與兒童聲調與元音習得的關係，及兒向語的非語言與語言層次互動問題。

Infant-directed speech (IDS) is the most significant speech input in early child language acquisition. A body of literature has explored the phonetic characteristics of tones and vowels in IDS, but little attention is paid to the interaction between tone and vowel in IDS. Thus, based on Hakka, this study attempts to investigate the interaction between tone and vowel, with an examination of phonetic manifestations of tones and vowels in Hakka IDS. Fourteen mother-infant dyads joined this study. They interacted with their infants and the researcher naturally at homes. These speeches were recorded as IDS and adult-directed speech (ADS). Speech stimuli used in this study contained 18 disyllabic phrases, in which the first syllables were the targets. For each ADS/IDS, the first two clear tokens of each target syllable were segmented for acoustic analysis of the values of fundamental frequency (F0) and the first two formants (F1 and F2) by PRAAT. After that, these F0, F1 and F2 values were normalized for further analysis. Research results pointed out the following findings. First, compared with ADS, IDS displayed phonetically expanded tones in terms of F0 mean, F0 range, F0 contour and F0 slope. Second, compared with ADS, IDS displayed significant vowel lengthening. However, different from related literature, the study showed downward-moving vowel triangles, reduced vowel space areas and shortened cross-vowel acoustic distances. Third, the intrinsic pitch difference of vowels did not affect the tones in IDS. Fourth, tones displayed definite effects upon vowel triangles and vowel space areas. The tonal features constituted an affecting hierarchy: [non-checked/checked] > [high/non-high] > [level/contour]. Finally, the findings from this study were extended further to some related issues in IDS, such as how IDS is linked to child tone/vowel acquisition, what is the relation between intimacy and high tone, and which dimension, paralinguistic or linguistic, is of primary significance in IDS.