Perception of the /t/-/k/ contrast by Mandarin-speaking children with Speech Sound Disorders

Mandarin-speaking children with speech sound disorders (SSD) often show difficulties in producing alveolar and velar plosives contrasts (e.g., /t/ vs. /k/). But it remains unclear whether such phonological disorder correlates with the perception of the contrast between alveolar and velar plosives. The present study assessed whether Mandarin-speaking children with SSD who substituted [t] for /k/ in production could perceptually distinguish between /t/ and /k/, and compared their results with those from typically developing children (TDC) and typically adults (TA). We adopted a categorical perception paradigm with a /ta/-/ka/ continuum. The continuum included nine stimuli, which were synthesized from a naturally-produced /ta/. The SSD, TDC, and TA groups completed both identification and discrimination tasks that required perceptual judgment of individual stimulus and pairs of stimuli from the continuum. The results showed that the TDC and TA groups showed typical patterns of categorical perception in the continuum. But the SSD group only reached or was slightly above the chance level in the identification task and did not show significant difference among pairs of stimuli in the discrimination task. Their performance was significantly different from that of the TDC and TA groups and lacked typical patterns of categorical perception. The results suggested that their perception of /t/ vs. /k/ may be impaired. Considering the SSD group's speech errors, this perception defect may be a cause for their tendency of substituting [t] for /k/ in production.