台灣華語鼻音韻尾合流的語料庫研究分析

Revisiting Nasal Coda Merger in Taiwan Mandarin: A Corpus Study

台灣華語鼻韻尾合流的文獻中，許多文獻聚焦在討論不同發音位置的鼻韻尾合流和語者的語言背景等社會語言學的關連性。但本研究將焦點拉回最基本的討論：台灣華語的鼻韻尾[-n]與[-ŋ]在聲學特徵上是否仍保持著位置上的對比抑或是已呈現合流，以及哪些聲學特徵可以如實呈現鼻音韻尾發音位置的對比。本研究使用大量的語料庫語音資料進行聲學分析，研究結果顯示，鼻音韻尾呈現不完全合流，而且單獨使用頻率走向或鼻音噪音解釋在台灣華語中鼻音發音位置的對比是不足的。其中不同位置的元音各自使用不同的聲學特徵去維持發音位置的對立，例如：若單看頻率走向或是鼻音噪音位置，央元音後的鼻音韻尾發音位置的聲學特徵趨向中合弱化，但卻可區辨低元音後的鼻音韻尾的發音位置。

Taiwan Mandarin allows two nasal codas, [n] and [ŋ]. Previous studies revealed that possible place merger is correlated to sociolinguistic factors. To test whether incomplete neutralization of place contrasts occur acoustically, this study examines potential mergers by questioning whether words with nasal codas are truly merged. By using fine-grained acoustic analysis on a spoken corpus, we discovered that in many cases where neutralization was assumed, sounds are actually incompletely neutralized. Words with a mid vowel preceding the nasal coda tend to be phonetically reduced in connected speech (shortened in nasal murmur duration and produced with the least variation), while words with a low vowel preceding the nasal coda depend on the following place of articulation. Results provide evidence that various vowel heights use different acoustic correlates to maintain place distinctiveness; formant transition and nasal murmur alone are not enough to account for place contrasts in nasal codas in Taiwan Mandarin.