Some acoustic aspects of early imitation of speech: F0 and vowels

Abstract

A Japanese mother and her infant son were recorded on high quality equipment in the home setting. The imitative utterances of the infant were analyzed acoustically and compared to the mother's. The intonation contours from age five weeks were found to reproduce acoustic characteristics of F0 frequency, pattern, and duration; apparently in that order of acquisition. It was also found that the mother raised her F0 from an average of 185 Hz to an average of 325 Hz when interacting with her child. 325 Hz is within the infant's own F0 range, apparently facilitating imitation. At approximately 11 weeks the child also began to spontaneously produce vowel sounds, and to imitate his mother's vowels. The infant vowels were frequency scaled, and not simple acoustic matches. The child could have reproduced some of his mother's vowels almost exactly, but instead finds a phonetic equivalence in an acoustic vowel space that is appropriate to his smaller supralaryngeal vocal tract. [Work supported by NICHHD.]