東勢大埔客家話兒向語與成人語擦音的聲學比較：兼談對華語文教學研究的啟示

An Acoustic Comparison of the Fricatives in Infant-Directed Speech and Adult-Directed Speech of Dongshi Hakka and Its Inspirations to the Study of Chinese Teaching and Learning

綜觀歷來的兒向語語音研究，大多著重於元音與韻律的探究，輔音則較少受到重視。因此，本研究將以東勢大埔客家話中的擦音[s，∫]為研究標的，比較擦音的摩擦噪音時長、頻譜能量高峰頻率及音節比在兒向語與成人語中的語音表現，並考量不同的後接元音（[i, a, u]）、不同身份的照護者（媽媽、爸爸、保姆）、不同的月份別等因素對擦音的影響。本研究的參與人員包括9 位說東勢大埔客家話的成人及其嬰兒的配對（每種身份各3 位）。成人語與兒向語的錄製從嬰兒3 個月大開始到嬰兒12 個月大為止，每3 個月進行一次錄音，最後利用PRAAT 進行相關聲學參數的測量。本研究的發現如下：（一）摩擦噪音時長方面，不論哪一個因素，兒向語均明顯長於成人語。（二）頻譜能量高峰頻率方面，兒向語[∫]在所有因素裡均顯著高於成人語[∫]，但兒向語[s]與成人語[s]之間卻傾向無顯著差異。這種[s，∫]表現不一致與它們在頻譜特徵上的差異有關。（三）音節比方面，兒向語不大於成人語。（四）身份別方面，媽媽在兒向語裡的語音修正表現明顯優於爸爸和保姆。最後，本研究針對[s，∫]在兩種語體裡的表現差異提出解釋，並將結果與「語音提升」及語言習得的概念相連結，同時也探討了本研究的結果對華語文教學研究的啟示。

Earlier phonetic/acoustic studies in infant-directed speech (IDS) focused mainly on vowels and prosodic features, with relatively little attention directed to consonants. For this reason, this study targeted to exploring the phonetic realizations (i.e., the frication duration, spectral peak frequency, and fricative/syllable ratio) between adult-directed speech (ADS) and IDS under different factors (i.e., following vowels, caregivers, and months of infants’ age), based on the fricatives [s, ∫] in Dongshi Dapu Hakka. Nine adult-infant dyads (3 mothers, 3 fathers, and 3 babysitters) took part in ADS and IDS recordings which were conducted once three months from three to twelve moths of infants’ age. Fricatives’ frication duration, spectral peak frequency and fricative/syllable ratio were measured with PRAAT. This study showed the following results. First, as for frication duration, [s, ∫] in IDS was significantly longer than those in ADS in all influencing factors. Second, in terms of spectral peak frequency, IDS’ [∫] was higher than ADS’ [∫] significantly. However, [s] in ADS and IDS tended to show no significant difference. It was argued that the spectral inconsistency between [s] and [∫] may result from their difference in spectral characteristics. Third, as far as the ratio of fricatives to syllables was concerned, IDS was not larger than ADS. Fourth, in terms of caregivers, mothers showed better phonetic modifications in IDS than fathers and babysitters. Finally, this study provided accounts for different phonetic realizations of [s, ∫] between ADS and IDS, established a connection of the results to the concept of ‘phonetic enhancement’ and language acquisition, and discussed the inspirations of the current results to the studies of Chinese teaching and learning.