Maternal Accommodation in Infant-Directed Speech during Mother's and Twin-Infants' Vocal Interactions

In this study a mother's instinctive accommodations of vocal fundamental frequency (f₀) of infant-directed speech to two different infants was explored. Maternal speech directed to individual 3-mo.-old fraternal twin-infants was subjected to acoustic analysis. Natural samples of infant-directed speech were recorded at home. There were differences in the rate of infants' vocal responses. The mother changed her f₀ and patterns of intonation contour when she spoke to each infant. When she spoke to the infant whose vocal response was less frequent than the other infant, she used a higher mean f₀ and a rising intonation contour more than when she spoke to the other infant. The result suggested that the mother's speech characteristic is not inflexible and that the mother may use a higher f₀ and rising contour as a strategy to elicit an infant's less frequent vocal response.