AGE-RELATED CHANGE IN JAPANESE MATERNAL INFANT-DIRECTED SPEECH AND INFANT'S VOCAL RESPONSE
Katsuko Niwano, Kuniaki Sugai · Hokkaido University Collection of Scholarly and Academic Papers (Hokkaido University) · 2002
We have investigated how maternal infant-directed speech shows age-related change, and which acoustic features of maternal infant-directed speech elicit an infant's vocal response effectively during the prelinguistic period.Voice samples of 50 Japanese mother and infant dyads were recorded during the first 9 months of the infant's life longitudinally.Fundamental frequency (fo) from the mother's speech and the infant's vocalization during mother-infant interaction were extracted and analyzed using an acoustic analyzer.The acoustical features measured in this study were the mean f 0, f 0 -range, and the intonation contour.We found age-related change in the prosodic features of mother's speech.The mothers changed fo in their infant-directed speech during months 3-5, and 7-9 postnatally, and they changed fo-range during months 5-7 postnatally.They showed a falling pattern of intonation contour most frequently during age 3 and 7 months and a rising pattern appeared most frequently at the ,infant was 9 months old.The infant's response also showed age-related change.Three-month-old infants tended to respond to the maternal speech with any value of f 0 and f 0 -range.In contrast, 9-month-old infants tended to respond to the speech with higher f 0, more exaggerated f 0 -change, and a rising pattern of intonation contour selectively.The results suggest that the change in acoustic features of maternal speech reflects the infant's perceptual and linguistic development.