Acoustic correlates of individuality in the cries of human infants.

The acoustic features that differentiate the cries of individual human infants were examined in this study. A recognition task, performed by 400 nonparent adults, was used to classify twenty 30-day-old infants as easy or difficult to recognize on the sole basis of their tape-recorded cries. The cries of easy- vs difficult-to-recognize infants were then compared on measures of duration, fundamental frequency, peak frequency in the spectrum, signal-to-noise ratios, and energy in selected frequency bands. The results indicated that each of these measures differentiated the cries of easy- vs difficult-to-recognize infants. Such redundancy should make the cry robust to degradations of selected acoustic parameters, thus enhancing its ability to carry information about individual identity across distances.