Categorical perception of post-alveolar sibilants by Taiwan and Beijing Mandarin speakers

Résumé

This study investigates how dialect-specific phonetic variation affects speech perception. Previous studies have pointed out that the contrast between dental and retroflex sibilants tends to be lost in connected speech in Taiwan Mandarin, while the contrast is maintained in Beijing Mandarin (Chang 2013, Noguchi et al. 2015). A study has demonstrated that, due to the merger, Taiwan speakers have a broader/weaker category for the retroflex sibilant relative to the dental sibilant (Chang 2013). In this study, we test whether the weakness of the category affects the perception of retroflex sibilants relative to the other class of sibilant in the inventory of Mandarin phonemes. Specifically, we compared Taiwan and Beijing Mandarin speakers on their perception of retroflex [?] and alveolopalatal [?]. The experiment consisted of two tasks: identification and an ABX discrimination tasks in which participants compared a sound to two sounds that were separated by 2 steps. Stimuli were drawn from a 10-step continuum from retroflex [?a] to alveolopalatal [?a]. Overall results showed that the two groups of speakers did not differ in their perception of the sibilants. In the identification task, both groups evinced the same category boundary location (step 6). In the ABX discrimination task, both groups showed the highest sensitivity to the difference between stimuli that straddled the category boundary (i.e., step 5 vs. step 7). Taken together, the data indicate that  both groups perceived the continuum in a categorical manner, and that the boundary between the categories was the same for the 2 groups. Beijing speakers, however, showed slightly better sensitivity to difference between stimuli drawn from the alveolopalatal end (e.g. step 6 vs. step 8).