Perceptual differences in infant cries revealed by modifications of acoustic features.

Previous studies of infant cry acoustics and their perceptual significance have remained inconclusive as to the graded nature of cry production and perception and to the exact role and importance of particular acoustic features. In this study, a set of infant cries were digitally analyzed and resynthesized to form natural-sounding cries with varying fundamental frequency (F0), degrees of jitter (period to period variations in F0), and rise time (time for F0 to reach its maximum value). In a perceptual rating task, higher-F0 cries as well as cries with larger amounts of jitter tended to be given more negative ratings than were lower-F0 cries and cries with less jitter, respectively. The perceptual ratings of the rise time manipulations were inconclusive. This study demonstrated a perceptual effect of F0 and jitter independently of other parameters, consistent with current notions of infant cry gradedness. It was also shown that digital signal processing techniques can be fruitfully applied to infant cry research.