The aim of designing sentences with special tone combinations is to investigate the declination tendency of intonation in Chinese Putonghua.The result shows that baselines of prosodic phrases（PP）,as the basic declination units,show the phenomena of declination clearly,and the declination slope is in inverse proportion to the length of PP.Different tone combinations of PP have different declination slopes.The primary conclusions are as follows： （1） If low points are at the beginning of prosodic word（PW）,the absolute value of baseline slope is larger than those at the end;（2） The declination of PP is larger,if it is at the beginning of sentences than that at the end;（3） When there are several PPs in sentences,although in different syntactic relations the degree of declination is different,they have the common ground of PP declination.
A phonetic experiment was conducted to investigate whether the acoustic features of discourse focus were subjected to the influence of discourse hierarchy. Six speakers were instructed to read aloud 32 groups of experimental material. The duration, pitch range, f0 maxima, and f0 minima of foci in different discourse hierarchies were extracted for statistical analysis. The results revealed that foci embedded higher in the discourse hierarchy had relatively longer duration and more expanded pitch range; moreover, with the variation of tone combination, foci in different discourse hierarchies differed remarkably in their manifestation of f0 maxima and f0 minima features. Specifically speaking, for non-low tone combinations, foci in higher discourse hierarchy were pronounced with higher f0 maxima, while for low-tone combinations, foci in higher discourse hierarchy were articulated with lower f0 minima.
Relying on a corpus of thirty narrative discourses, the roles of pitch and duration of prosodic words in sentence accent were studied in discourse context. At first, the pitch was normalized. Then according to the pitch range, the sentence and prosodic word were classified into three ranks of strengthened, normal and weakened respectively. In the same time the sentence accent was classified into two levels of primary and secondary by perceptual evaluation. The results showed that the relative pitch range of prosodic words in opposition to sentence contributed dominantly to sentence accent. Furthermore, the roles of pitch and duration in sentence accent were affected interactively by the rank of sentence and prosodic words. In normal prosodic words, primary sentence accents were realized by the mutual performance of pitch and duration while secondary sentence accents mainly depended on the variation of pitch. In strengthened prosodic words, the role of duration in sentence accent was more significant when the pitch range of the sentence was more compressed. Finally, it was found that the correlation between pitch and duration was influenced primarily by the strength of prosodic words, and in weakened, normal and strengthened prosodic words, the correlations between pitch and duration were positive, null, and negative respectively.
