Fear B D, Cutler A, Butterfield S
Department of Engineering, University of Cambridge, United Kingdom.
J Acoust Soc Am. 1995 Mar;97(3):1893-904. doi: 10.1121/1.412063.
Strong and weak syllables in English can be distinguished on the basis of vowel quality, of stress, or of both factors. Critical for deciding between these factors are syllables containing unstressed unreduced vowels, such as the first syllable of automata. In this study 12 speakers produced sentences containing matched sets of words with initial vowels ranging from stressed to reduced, at normal and at fast speech rates. Measurements of the duration, intensity, F0, and spectral characteristics of the word-initial vowels showed that unstressed unreduced vowels differed significantly from both stressed and reduced vowels. This result held true across speaker sex and dialect. The vowels produced by one speaker were then cross-spliced across the words within each set, and the resulting words' acceptability was rated by listeners. In general, cross-spliced words were only rated significantly less acceptable than unspliced words when reduced vowels interchanged with any other vowel. Correlations between rated acceptability and acoustic characteristics of the cross-spliced words demonstrated that listeners were attending to duration, intensity, and spectral characteristics. Together these results suggest that unstressed unreduced vowels in English pattern differently from both stressed and reduced vowels, so that no acoustic support for a binary categorical distinction exists; nevertheless, listeners make such a distinction, grouping unstressed unreduced vowels by preference with stressed vowels.
英语中的强音节和弱音节可以根据元音音质、重音或这两个因素来区分。对于在这些因素之间做出决定至关重要的是包含非重读音节未弱化元音的音节，比如“automata”的第一个音节。在本研究中，12名说话者以正常语速和快速语速说出包含匹配单词集的句子，这些单词的首元音从重读到弱化不等。对单词首元音的时长、强度、基频和频谱特征的测量表明，非重读音节未弱化元音与重读元音和弱化元音均有显著差异。这一结果在不同性别和方言的说话者中都成立。然后，将一名说话者发出的元音在每组单词中进行交叉拼接，并让听众对生成单词的可接受性进行评分。一般来说，只有当弱化元音与其他任何元音互换时，交叉拼接单词的评分才会明显低于未拼接单词。交叉拼接单词的评分可接受性与声学特征之间的相关性表明，听众关注的是时长、强度和频谱特征。这些结果共同表明，英语中非重读音节未弱化元音的模式与重读元音和弱化元音不同，因此不存在对二元分类区分的声学支持；然而，听众会做出这样的区分，更倾向于将非重读音节未弱化元音与重读元音归为一组。
