The Effect of Sibilant Merger on Phoneme Categorization in Taiwan Mandarin?

While studies on the Ganong effect in speech perception have been extensively replicated, there is a scarcity of evidence establishing a connection between the dynamic nature of sound change. The current study investigates native listeners’ phoneme categorization of the alveolar-retroflex sibilant merger in Taiwan Mandarin (TM) by conducting a two-alternative forced-choice identification experiment. Continua includes each sibilant as gap end as well as both words endpoints to examine lexicality, frequency, and the influence of de-retroflexed variants of gap signals of phoneme categorization. The findings of the study indicate that in the context of the merging process, the alveolar sibilants tend to be perceived as "de-retroflexed" variants of the retroflex sibilants, attributed to the unidirectional nature of the merging process. Furthermore, in continua where there is no lexicality effect, a bias towards the higher frequency end is observed. Collectively, these results enhance our comprehension of phoneme categorization in the context of merger, specifically in relation to the effects of gap and lexicality.