Kuo Christina
Department of Communicative Disorders and Waisman Center, University of Wisconsin-Madison, Madison, Wisc., USA.
Folia Phoniatr Logop. 2013;65(4):178-84. doi: 10.1159/000356478. Epub 2013 Dec 19.
Acoustic characteristics associated with varied utterance positions were examined to understand the acoustic consequences of potential articulatory changes near utterance boundaries.
Second formant transition characteristics, including transition duration (ms), transition extent (Hz), and derived slope of transition (Hz/ms), of 12 healthy speakers of American English were examined for two diphthong transitions in sew and sigh and one consonant-vowel transition in bee in utterance-initial, utterance-final, and utterance-end positions. Speakers performed a task of contrastive stress variation that served to demonstrate the changeability of acoustic characteristics as an index of articulatory change in shaping the vocal tract.
Contrastive stress, as compared to words spoken without increased stress, was associated with longer transition duration, greater transition extent, and a decreased slope. Although some utterance position effects were present, no systematic differences consistent with boundary strengthening or declination were found.
Findings suggest that varied utterance positions may be associated with stimulus-dependent variation in articulatory changes that is reflected in the acoustic output. These results indicate the need to further understand the construct of utterance-level speech materials, such as carrier phrases, in clinical practice and research.
研究与不同话语位置相关的声学特征，以了解话语边界附近潜在发音变化的声学后果。
对12名以美式英语为母语的健康受试者，在话语起始、话语末尾和话语结束位置，考察了sew和sigh中两个双元音过渡以及bee中一个辅音-元音过渡的第二共振峰过渡特征，包括过渡时长（毫秒）、过渡幅度（赫兹）和过渡的派生斜率（赫兹/毫秒）。受试者执行了对比重音变化任务，该任务用于证明声学特征的可变性，作为发音变化在塑造声道时的一个指标。
与未加重音的单词相比，对比重音与更长的过渡时长、更大的过渡幅度和减小的斜率相关。尽管存在一些话语位置效应，但未发现与边界强化或下降一致的系统差异。
研究结果表明，不同的话语位置可能与发音变化中依赖刺激的变化相关，这在声学输出中有所体现。这些结果表明，在临床实践和研究中，有必要进一步理解话语层面言语材料（如载体短语）的结构。
