The IF0 effect in the Hong Kong Cantonese tone system

This study investigates intrinsic fundamental frequency (IF0) in Hong Kong Cantonese tones. Given the tension between exaggerating IF0 to enhance vowel contrasts and restraining IF0 to distinguish confusable tone pairs, the investigation 1) examines the relationship between IF0 and tone merging and 2) tests the mixed physiological-enhancement hypothesis (MPEH) that IF0 is physiologically determined, but adjusted to enhance perception of contrasts. When F0 measurements of vowels are fit to Generalized Additive Mixed Models (GAMM), the results suggest that the confusable tone pairs are at the beginning of a tone-merging process. The size of the IF0 effect varies as follows: T2 > T1/T5 > T3/T6, which supports MPEH to some extent. However, IF0 of T4 and individual speaker performance cannot be fully explained by MPEH. Future research is needed to elucidate the IF0 mechanism and the relationship between IF0 and tone merging.