RHYTHMIC ORGANIZATION OF THE SOUND OF INFANT CRYING

The purpose of the present study was to examine the temporal morpholog y and rhythmic structure underlying the repeated bursts of expiratory sounds in a sustained bout of crying of twenty-three 1-month-old infan ts. Durations of expiratory sounds and bursts were determined from a 9 0-s bout of naturally occurring cries recorded in the home before feed ing. Results indicated wide individual differences in temporal morphol ogy between infants and within infant cry sounds. Binary spectrum anal ysis of the presence of expiratory sounds in the cry sound detected rh ythms in temporal organization at a wide range of dominant frequencies . Spectral complexity (higher numbers of peaks in the power spectrum) was related to a longer time since infants were last fed and shorter e xpiratory sounds. Results emphasize the importance of viewing cries of young infants as dynamic signals. An ontogenetic history of the rhyth ms of infant cry sounds may contribute to understanding organismic and environmental experiences which contribute to development. (C) 1993 J ohn Wiley & Sons, Inc.