The Role of Lexical Contrast in the Perception of Intonational Prominence in Japanese
This dissertation has been moved to the following series:
In this dissertation, I examine the effects of lexical accent on the perception of intonational prominence in Japanese. I look at how an F0 accent peak is perceived relative to another flanking F0 peak in the same utterance with respect to perceived intonational prominence. Through four experiments, I show that the lexical prosodic structure plays a significant role in the perception of intonational prominence. I first show that two distinct perceptual processes are at play in the perception of relative perceived prominence in Japanese: accentual boost normalization and downstep normalization . Accentual boost normalization normalizes the accentual boost of an accented word. In this process, the extra F0 boost assigned by a lexical accent does not count as part of the F0 peak's excursion that contributes to the perceived prominence of the F0 peak. I demonstrate that when an accented word and an unaccented word are perceived as having the same prominence, the accented word has a higher F0 peak value than the unaccented word does. Downstep normalization compensates for the production effect of downstep, a pitch range compression phenomenon after a lexical accent. Experiments show that for an F0 peak to be perceived as having equivalent prominence to a preceding F0 peak, the second peak is always lower in F0 when the first word is accented than when it is unaccented. This suggests the existence of a perceptual process that normalizes the effect of downstep. I then examine the nature of accentual boost normalization and downstep normalization and show that they refer to two distinct types of lexical accent property when they are applied. One is the phonetic F0 contour shape that is characteristic of accented words. The other is the phonological lexical accent information that is uniquely specified for accented words. The experimental results show that the perceptual effects of the normalization processes are seen when only the phonological lexical accent information of a word is present with its F0 contour shape being ambiguous as well as when the same word is acoustically manipulated into different F0 contour shapes.