Effect of exposure on production and perception of ongoing level tone mergers in Hong Kong Cantonese

This paper examines the plasticity of speech production and perception in sound change. It focuses on the merger between the mid-level (T3) and low-level tones (T6) in Hong Kong Cantonese and investigates 1) whether exposure to an unmerged talker affects the production and perception of this tonal contrast and 2) how speakers’ baseline performance interacts with the exposure effect. Fourteen young speakers (F=10) participated in four production blocks (baseline, two shadowing blocks,
post-task) in which they read T3 and T6 monosyllables as well as AX discrimination tasks on T3/T6 minimal pairs. Significant exposure effect was only found in production among speakers who were more merged in the baseline production: T3/T6 difference was significantly greater in the shadowing and post-task blocks compared to the baseline. No exposure effect was found for perception. This finding indicates that the plasticity of speech production in sound change is likely subject to phonological constraints.