Exploring the causes of entering tone loss based on interaction density: An analysis on two datasets of the Fen River Basin, China

This study investigated the quantitative changes in the retention of entering tone words in the Lingshi Highlands, which are located in the central Fen River basin of Shanxi Province, China. Our findings suggested that the entering tone is progressively decreasing at varying rates across five dialect regions. However, it remained unclear whether this decrease was due to the influence of the central dialect or the independent development of each local dialect, as well as what factors contributed to the discrepancy in the rate of decrease. To address these issues, this study proposed that the interaction density determines the extent of linguistic change. The interaction density serves as a quantification of the frequency at which people from diverse dialect regions engage in communication with those from central region. The results revealed that the interaction density ranking of each dialect region in the Lingshi Highlands, and the central dialect region aligned with the ranking of number of entering tone words remaining in these regions. This suggested that the disappearance of the entering tone in Middle Chinese was not caused by independent changes within each dialect, but rather by the influence of the central dialect. Furthermore, the hypothesis that the interaction density determines the extent of linguistic change was supported by the data obtained from a follow-up survey in the same Lingshi Highlands in 2022.