This chapter reviews some important outcomes of developmental research on Japanese phonology, particularly in the area of early production. The review highlights the acquisition of several phonological phenomena in Japanese that are of particular interest from a crosslinguistic perspective, such as durational contrasts, mora-timing, and pitch accent. These are aspects in which Japanese differs typologically from English and several other European languages whose developmental data have been the empirical foundation of much theorizing in language acquisition. As such, the acquisition of these properties provides complementary evidence and insights that can further our general understanding of phonological development.
Development of the segmental inventory
Recent research on early speech production shows that language-specific segmental inventories begin to take shape during the babbling stage. Japanese is no exception. Babbling vocalizations in Japanese contain more nasals in comparison to those in English or Swedish, and fewer labials in comparison to those in French or English (Boysson-Bardies & Vihman, 1991). These findings indicate that children exposed to Japanese are tuning into the frequency distribution of the target segments even before they produce their first words.
Despite this precocious sensitivity to the language-specific phonemic inventory, children do not produce all segments or contrasts from the initial stages of word production. The order in which targetlike production of Japanese segments is achieved has been investigated in a number of cross-sectional studies, typically by means of a word elicitation task and accuracy measurement based on phonetic transcription (e.g. Murata, 1970; Nakajima et al., 1962; Owada, Nakanishi & Oshige, 1969; Sakauchi, 1967; Umebayashi & Takagi, 1965).