Declination and tone perception in Cantonese

This paper first provides an overview of declination and Cantonese before proceeding to report a perception experiment studying the effect of declination on tone identification. In Cantonese, there are four level tones (High, High Mid, Mid Low and Low Fall). These tones differ from one another in terms of pitch height. Of these four level tones, the High Mid and the Mid Low tones are fairly close to one another in terms of pitch height. It is reported that this pair is the most easily confusable in Cantonese. It is known that declination affects pitch height/level of a tone over time. Time is defined in terms of utterance positions. Given the effect of declination, it is likely that an F(0) value can be interpreted as an early-occurring Mid Low tone as well as a late-occurring High Mid tone. By examining the way listeners employ a base line and a top line in compensating for declination prior to mapping F(0) to the pair of High Mid and Mid Low tones, this paper proposes that both base line and top line are used to derive a local pitch range against which F(0) is scaled and mapped onto the tones in an utterance.