The Wave Model and the Spatial Diffusion of a Dialectal Change in the Red River Delta

Abstract

This article investigates the spatial diffusion of the merger between retroflex consonants /ʈ/, /ş/, /ʐ/ with their corresponding laminal/apical counterparts (/c/, /s/, /z/) in the Red River Delta, employing the theoretical framework of the Wave Model. Utilizing survey data from 344 residential locations processed via ArcGIS Online, the study analyzes the distribution of phonetic variants in relation to geographical and social factors. The findings identify Hanoi as the primary innovation center from which the phonetic merger wave originates most strongly. The linguistic change spreads through a neighboring effect, with merger rates decreasing as the distance from the innovation center increases. Remote coastal and semi-mountainous regions currently serve as relic areas, preserving archaic phonetic features due to braking effects and time lags. The study concludes that the phonetic landscape of this region is a dialect continuum undergoing gradual "leveling" driven by innovative impulses from the center.