Point vowels in Japanese mothers’ speech to infants and adults

American, Russian, and Swedish mothers produce acoustically more extreme point vowels (/i/, /u/, and /a/) when speaking to their infants than when speaking to another adult [Kuhl et al., Science 277, 684–686]. This study examines the three point vowels in Japanese mothers’ speech, and compares the acoustic structure of infant-directed (ID) and adult-directed (AD) tokens. Three target words containing /i/, /u/, and /a/ (bi:zu, batto, bu:tsu = beads, bat, boots) were recorded while mothers conversed with another native-speaking adult, and with their infants, aged either 51/2 or 81/2 months. F1, F2, and F0 were measured at vowel onset, center, and offset. Acoustic, results will be compared for AD and ID speech, and expansion of the vowel space in Japanese mothers’ speech will be examined. [Work supported by NIH HD35465-01S1.]