Separated and reunified: An apparent time investigation of the voice quality differences between Hong Kong Cantonese and Guangzhou Cantonese

Hong Kong Cantonese (HKC) and Guangzhou Cantonese (GZC) are two major accents of Cantonese spoken in two geographically non-contiguous cities in Southern China. Previous studies were unable to identify the phonetic features that discern the two accents since they share the same phonological system. This study attempted to solve the puzzle by investigating the voice quality differences between the two accents through acoustic analysis on the speech output of 191 talkers in three age groups ranging from 18 to 65 years old. Among the various spectral and noise measurements of voice quality, we found that Cepstral Peak Prominence (CPP) was the best acoustic measure to discern the two accents. Based on the CPP measure, GZC had overall increased noise than HKC. Covariation of voice quality and tones was studied. The greatest CPP differences between the two accents were found in the two extreme tones: the high-level and the extra-low-level tones. Furthermore, creaky voice was found mainly tied to the extra-low-level tone in both accents. However, HKC exhibited higher frequency of creaky voice than GZC. The creaky voice in GZC was characterized by increased noise and increased tension, compared to those of HKC. Finally, age was found to be a mediating factor in the voice quality of the two accents. Adopting the Apparent Time Framework, voice quality in the two cities has undergone changes over time. The voice quality of the young generations of the two accents have become merged among the three low tones. Furthermore, the prevalence of creaky voice was increasing across age groups in both accents, and it increased at a faster rate in HKC than GZC.