语篇中大尺度信息单元边界的声学线索

The acoustic characteristics of large information units' boundaries in monologue discourse

主要研究了语篇中句子、段落等大尺度信息单元边界的韵律等级以及边界处的声学线索。对10个语篇语料库进行了韵律等级标注和声学分析。研究得到以下主要结论: (1)语篇中有韵律意义的大尺度信息单元有小句(对应语调短语)、句子(包括单句和复句)和段落。单句和复句边界没有知觉等级和声学特征上的显著区别,对应同一韵律单元。 (2)大尺度韵律边界等级的音高线索是通过边界前后音节的音高对比实现的,即音高重置程度。仅有首音节或末音节处的单一声学线索不足以区分边界等级。(3)段落和复句内的语调短语基本以平行的模式存在,没有明显的、规律性的整体语调下倾的现象。 (4)信息单元越大,无声段越长且变化的自由度越大。另外,在小句边界处无声段与音高重置程度显著正相关。

The acoustic characteristics and the perceived boundary strength of information unit boundaries in monologues are studied. The studied information units were clauses, sentences and paragraphs. The acoustic analysis was based on a prosodically labeled corpus of ten monologues. The main results were as follows: (a) There is a significant difference in the perceived degree of boundary strength for clauses (corresponding to intonational phrase), sentences (including simple sentences and complex sentences) and paragraphs. There is no significant difference in the perceived degree of the boundary strength at the edges of simple and complex sentences, nor is there significant difference in the acoustic variables measured (e.g. pitch reset and silence), suggesting that simple and complex sentences constitute a single type of prosodic constituent. (b) The pitch-based cue used to distinguish between different information units appears to be the difference between pre- and post-boundary syllables, but not simply the pitch of either syllable alone. (c) Declination occurs within intonational phrases, but not across or between larger units. (d) Silent pauses are longer and more varied between larger units. Moreover, there is a significant positive correlation between silent pause duration and the degree of pitch reset at clause boundary.