Proceedings of ICSP ’ 96

FO contours tend to decline over the course of a major intonation phrase’ (MaIP). These FO downtrends form an envelope decomposed of a baseline and a top-line ( Pierrhumbert 1980, Maeda 1976,Cohen and t’Hart 1967). The baseline declination is a non -uniform function. That is, the slope of its angle is greater at the lower level constituents boundaries of the prosodic structure, e.g. at the edge of Noun Phrase that forms a prosodic boundary, i.e. at the edge of a minor intonation phrase(Mi1P); while its gradient is smaller for the rest of the utterance. The top-line, on the other hand, has a steplike reduction per peak. This compresses the pitch range much greater than the baseline. Application of the downstep rules can result in high quality synthetic speech.