Newborns crying in different contexts: discrete or graded signals?

The aim of this study was to investigate whether human infants' cries show individually and contextually discriminable acoustic parameters. 20 full-term normal human newborns (aged 1 to 4 days) had their cries recorded during routine blood withdrawal (pain context) 30 min. before a scheduled feeding (hunger context) and when subjected to kinetic stimuli during neurological examination (manipulation context). Type of cries, melodic contours, F0 parameters, but not the "macro" trend of the start of the fundamental frequency, indicated a difference in pain cries in the other two contexts. All the acoustic features considered showed an individual specificity. The peak frequencies of voiceless or partially voiced wails had the interesting property of being optimised as long distance signals. We hypothesised that this feature of infants' cries may have evolved in a time window when the infants were left in collective nurseries and not carried on the mothers' backs as maintained by the traditional view.