Speech Prosody 2008
In a corpus study using eight pairs of syntactically ambiguous sentences, we conducted acoustic and quantitative analyses of the prosodic patterns used by seven native speakers of the Hong Kong variety of Cantonese to divide these sentences into prosodic words - a phenomenon referred to as "prosodic chunking". Although pauses, pitch reset and preboundary lengthening were analyzed, in this article we concentrate on presenting results from the analysis of preboundary lengthening. Using test sentence pairs consisting of identical series of words with two possible prosodic subdivisions, we measure the preboundary syllables within the sentence, and compare it to the same syllables in the non-boundary position of the corresponding sentence. Results indicate that the presence/absence of a following prosodic boundary is highly significant in the measure of lengthening, thus confirming preboundary lengthening as a prominent device in marking prosodic word boundaries in Cantonese. Moreover, the presence of a pause at the prosodic word boundary also triggers a more prominent preboundary lengthening. Finally, our statistical results indicate that there seems to be a trade-off relation between pitch reset and preboundary lengthening. Since this result seems to contradict with recent research, which indicates that pitch range increases with syllabic duration , and that pitch contours are also subject to contextual tonal effects (both carry-over and anticipatory)  as well as perturbations brought about by focus . As a result, more research is needed before we can confirm/disconfirm the validity of this trade-off relation.
Bibliographic reference. Chow, Ivan (2008): "Quantitative analysis of preboundary lengthening in Cantonese", In SP-2008, 543-546.