Infant cry: a clue to diagnosis.

It has been postulated that the infant cry is a reflection of complex neurophysiologic functions and that analysis of the infant cry can be utilized to assess the infant's status. To test this hypothesis a model of cry production was developed utilizing a computer-based signal processing system that enabled the observer to relate closely the acoustic properties of the cry to the anatomic and physiologic characteristics of the infant producing the cry. The cries of 87 infants were analyzed following a standardized pain stimulus. Cry features were grouped into eight evaluative tests. Only seven of 55 apparently normal term infants had the abnormality "glottal instability" whereas 11 of 12 infants with bilirubin values in the 10 to 20 mg/100 ml range displayed the glottal instability pattern. An additional group of 17 infants with a variety of problems was studied; 14 of 17 displayed two or more abnormalities, and ten of 12 infants with respiratory disease had a unique pattern. Of particular interest was the finding of acoustical features suggestive of a constriction in the vocal tract in three infants; two of these infants were studied prospectively and subsequently were victims of sudden infant death syndrome and the third had a sibling with recurrent apnea. These results suggest that the analysis of the infant cry holds promise for detecting a number of abnormalities and may prove valuable as screening test to detect infants at risk for sudden infant death syndrome.