Early Acquisition of Palato-Alveolar Consonants in Japanese: Phoneme Frequencies in Child-Directed Speech

Abstract

Segmental development in infants is inevitably governed by universal constraints due to infants’ immature articulatory system, while auditory input builds up language-specific constraints. Since Jakobson (1968) first proposed the universal order of language acquisition, the universal tendency for children to acquire vowels, then nasals, glides (j, w) and labial consonants, followed by the consonants produced at the back of the oral cavity has been recognized. If the size of the tongue or the oral cavity is the only cause for children’s mispronunciation, the order of language acquisition should be the same across languages. However, cross-linguistic differences in the order of phoneme acquisition has been reported in various studies (Rice and Avey 1995, Ingram 1999, Stokes and Wong 2002, Zhu 2002, Beckman et al. 2003, Tsurutani 2004). If we presuppose that the individual differences in children’s physical development or traits are not linguistically significant, diverse patterns of development among languages of the world can be attributed to differences in the phonology of each language. Infants’ linguistic skills are shaped by auditory input from the ambient language (Vihman 1996). Their perception capacity to discriminate between speech sounds declines or is modified as they acquire the phonological system of the language (Wenker and Tees 1984). It is highly likely that the order of language acquisition is affected by language-specific factors in the input. Some studies (Pye et al. 1987, Vihman 1996, Beckman et al. 2003) have discussed the relevance of frequency of occurrence or phonological saliency to the order of phoneme acquisition. However, researchers have not reached a conclusive theoretical explanation. We may presume, then, that the investigation of sounds acquired in the earlier stage of language acquisition than the universal order would provide some clarification on this issue. Japanese palato-alveolar consonants have been chosen for this study since Japanese language is linguistically quite different from English and most other languages, and early acquisition in Japanese could present an instructive contrast to early acquisition of other languages. This study investigates the frequency of palato-alveolar consonants in child-directed speech and the phonetic environments where these consonants are used. Findings from this empirical study are then used to consider languagespecific factors that affect aspects of sound acquisition.