F0 downtrends [speech analysis and synthesis]

F0 contours tend to decline over the course of a major intonation phrase (MaIP). These F0 downtrends form an envelope decomposed of a baseline and a top-line. 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 the noun phrase that forms a prosodic boundary, i.e. at the edge of a minor intonation phrase (MiIP); 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