Cortisol Level and Acoustic Features of Cries in Japanese Newborns.

The present study was conducted to evaluate cry features and cortisol level in 10 healthy, full-term male newborns. For each of them, a total of 10 10-min vocal recording sessions were undertaken when spontaneous crying was displayed. Simultaneously saliva was collected from the subject. The results indicated that the duration of cries and the amount of dysphonation in cries were highly correlated with cortisol level in every infant. When the cortisol level was higher, the cry segments were likely to be longer and dysphonated more frequently. However, the fundamental frequency measures did not show such correlations. The significance of these results are discussed with reference to findings of previous studies on cry perception.