Total: 1
The development of allophonic variants of phonemes is poorly understood. This study aimed to examine when the allophonic variants of a phoneme are realized like adults. Japanese children aged 5–13 years and adults participated in an elicited production task. We analyzed developmental changes in allophonic variation of the phoneme /z/, which is realized variably either as an affricate or a fricative. The results revealed that children aged nine years or younger realized /z/ as affricate significantly more than 13-year-old and adult speakers. Once the children reached 11 years of age, the difference compared to adults was not statistically significant, which denotes a similar developmental pattern as that of speech motor control (e.g., lip and jaw) and cognitive-linguistic skill. Moreover, we examined whether the developmental changes of allophonic realization of /z/ are due to speech rate and the time to articulate /z/. The results showed that the allophonic realization of /z/ is not affected by those factors, different from that of adults. We also found that the effects of speech rate and the time to articulate /z/ on the allophonic realization become adult-like at around 11 years of age.