Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 23-28). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 71-78). Also available via the Internet.

The temporal organization underlying durational components of naturally occurring infant cries was examined in 46 1-month-old infants, half of whom had been diagnosed as having colic. In a standard 90-sec crying bout for each infant, the presence or absence of expired cry sound was determined at .05-sec intervals. Binary spectrum analysis of the data detected between 8 and 23 reliable cycles in the expiration of sound in the cries of all infants. The data were characterized by a wide range of individual differences in the frequencies at which these cycles occurred and in other characteristics of the spectra. Although infants with and without colic did not reliably differ in the mean, variability, or range of the durations of expirations or bursts, the two groups were distinguished by their distributions of the total number of peaks in the power spectrum and by the frequencies at which the highest power peak, slowest cycle, and fastest cycle occurred. This study provides the first known systematic examination of the rhythmicities underlying infant crying. / Master of Science

Crying is the primary source of distal communication through which newborn and young infants’ needs are related to the caregiving environment and, as such, this social behavior is vital to the survival and development of the infant. Recently, a series of experimental studies has begun to isolate the effects of specific durational components of crying on adults’ perceptions of infant cries. These studies have found the duration of pauses within and between cries to be perceptually salient features, however, the point at which adults were able to detect changes in the duration of the pauses was not addressed. Seventy-five introductory psychology students participated in three experiments designed to determine Difference Thresholds for the point at which manipulations in the durations of pauses before and after the inspiration in infant cries were detectable by the adult listener. The Difference Threshold for the pause before the inspiration (PBI) with the duration of the pause after the inspiration (PAI) held constant was an increase of 354.18% in the duration of the PBI. Difference Thresholds for increases and decreases in the duration of the PAI were 58.53% and -61.91%, respectively. For increases and decreases in the duration of the PAI with a perceptibly longer PBI, Difference Thresholds were 39.82% and -57.6%, respectively. The Difference Threshold for an increase in the duration of the PBI with a perceptibly shorter duration of the PAI was 420.06% and the Difference Threshold for a decrease in the duration of the PBI with a perceptibly longer duration of the PAI was 485.61%. Results provided the first known experimental evidence of the point at which changes in the durations of pauses before and after the inspiration in infant crying are detectable by adult listeners. / Master of Science