Infant frequency discrimination

Abstract

Frequency difference limens were determined for infants aged 5 to 8 months and for adults, at six tonal frequencies ranging from 250 to 8000 Hz, using the visually reinforced head-turn procedure. The relative difference threshold (threshold divided by frequency) was a nonmonotonic function of frequency with a minimum around 1000 Hz for both infants and adults. However, infant thresholds were twice those of adults at low frequencies but did not differ from adult values at high frequencies. Previously reported differences in absolute sensitivity at low frequencies are not great enough to account for the age difference in low frequency discrimination ability. These findings suggest that the auditory mechanisms responsible for frequency discrimination mature first at high frequencies, paralleling the base to apex sequence of prenatal development of hair cells and associated auditory nerve fibers.