Responsiveness to simple and complex auditory stimuli in the human newborn.

Abstract

AbstractThe relative effectiveness of complex and simple auditory signals was examined by presenting 2‐day‐old infants with a sequence of stimuli consisting of a white noise and a variety of pure tones (which ranged from 250 to 8000 Hz). “Catch” trials during which no stimulus was presented were interspersed throughout. The frequency of occurrence during “catch” trials of each of the response indicators (cardiac acceleration, toward‐turning eye movements, and finger movements) was used as the baseline. Although the white noise stimulus elicited significantly more responses on each of the measures than occurred during “catch” trials, none of the pure tones produced significant changes in baseline rates for any of the measures. Failure to obtain an effect on pure tone stimulation could have stemmed from an intensity effect. Therefore, an additional group of infants was examined using pure tones that ranged in intensity from 50 to 80 db (the intensity range covered by the relevant component frequencies in the white noise). None of these stimuli at any of the intensities used had an effect on any of the measures.