Near-merger in Hong Kong Cantonese tones: a behavioural and ERP study

Near-merger is a recalcitrant phenomenon in sound change in which speakers are able to differentiate two sounds in production but consistently report that they are the same in perception. This phenomenon challenges the dominant models of phonological processing, and raises methodological questions whether speakers’ judgment can truly reflect their ability to discriminate speech sounds. The present study attempts to provide a thorough assessment of this intriguing phenomenon through performing behavioural and ERP studies on the perception of a tonal contrast (T4/T6) in Hong Kong Cantonese which has been reported to exhibit near-merger in previous studies. The behavioural study adopts auditory discrimination and oral production tasks, whereas the ERP study employs passive oddball task to elicit MMNs. Preliminary findings showed that the results of ERP measures were consistent with that of the behavioural measures. MMNs were found in participants who could discriminate the two tones whereas no MMN was found in participants who failed to discriminate them behaviourally. These initial observations are not only consistent with the existence of near-merger, but also mark the beginning of research efforts into understanding this baffling phenomenon.