Acoustic analysis of cries from "normal" and "irritable" infants.

Infant irritability or colic is characterized by recurrent episodes of persistent, unexplained crying. The lack of a precise definition of the type and amount of cry that distinguishes an infant as colicky has hampered research and intervention efforts. The primary aims of this study are to describe the acoustic characteristics of cries of irritable infants and compare these to those of normal infants. Tape recorded cries of 11 irritable and 11 non-irritable infants were compared. The average age for infants of both groups was 8 weeks. The cries of irritable infants were higher in jitter, shimmer, proportion of noise, and tenseness than were the cries of control infants. Findings suggest that colic or infant irritability is more than just excessive crying. Acoustic characteristics of the cries of irritable infants reveal an increase in stress-arousal that supports the thesis of a state regulation disorder. Characterizing the nature and origin of the cries of irritable infants is essential to an understanding that will eventually guide appropriate diagnosis and management of these infants.