1987 Volume 28 Issue 3 Pages 162-169
The relationship between the vocalizations of early infants and their mothers was investigated based on acoustic analysis. The subjects were eight infants of 40-70 days old and their mothers. The infants were sufficiently developed to utter pleasure vocalization. Acoustic characteristics of the voices of both infants and mothers uttering in a state of sustained mother-infant interaction were analyzed, and the correlation between motherese and infant vocalization was examined in terms of pitch, duration, latency and melody types.
The results are the following.
1) Correlation was significant between the average fundamental frequencies of the infants' voices and those of their mothers. Motherese and infant vocalization tended to parallel with each other in terms of pitch.
2) There was little individual difference in the duration of infant vocalization, but a considerable individual difference in the duration of motherese. No correlation was observed in the duration of voices uttered by the infants and their mothers.
3) The latencies of infant vocalization and motherese showed large differences among the infant-mother pairs. There was a tendency for the latency of the motherese to affect the number of utterances by the infant.
4) Significant correlations among the melody types were observed in three motherinfant pairs.
These findings indicate that there are significant correlations in the exchange of voices between infants and their mothers, and that motherese affects the vocalization of infants remarkably.
