VOCALIZATION AND BREATHING DURING THE FIRST YEAR OF LIFE

Vocalization and breathing were studied in 40 healthy infants, includi ng five boys and five girls each at ages 5 weeks, 2.5 months, 6.5 mont hs, and 12 months. Breathing was monitored through the use of a variab le inductance plethysmograph that enabled estimates of the volume chan ges of the rib cage, abdomen, and lung, as well as estimates of select ed temporal features of the breathing cycle. Four vocalization types w ere studied intensively. These included cries, whimpers, grunts, and s yllable utterances. Breathing behavior was highly variable across the four vocalization types, demonstrating the degrees of freedom of perfo rmance available to the infant to accomplish the aeromechanical drive required. Such behavior was influenced by body length, body position, and age, but not by vocalization type and sex. The protocol establishe d is a useful tool for observing the natural course of the emergence o f vocalization and breathing during the first year of life.