Spectral energy distribution in four types of infant vocalizations

The distribution of spectral energy among four types of infant vocalizations was compared via computerized spectral analyses of "pain-induced," "fussy," and "hungry" cries and "cooing" of 30 2-6-month-old infants. Visual inspection indicated that "pain-induced" cries could be differentiated from "fussy" and "hungry" cries and that "cooing" could be differentiated from all cries on the bases of (1) the relative amplitude levels of the high-frequency components; (2) the average fundamental frequency; and (3) the overall spectral energy levels. Analysis of variance showed that (1) the mean spectral energy (MSE) levels of "pain-induced" cries were significantly higher than those of the other two types of cries and that the MSE of all three types of cries was significantly higher than that of cooing; and (2) that the mean spectral energy in any vocalization by 6-month-old infants of either sex was significantly lower than that in any vocalization of younger infants.