Temporal summation of 500-Hz tones and octave-band noise bursts in infants and adults.
A visually reinforced operant procedure was employed to obtain 2-point threshold-duration functions in 7-month-old infants and adults in two experimental paradigms. In Experiment 1, thresholds were determined for 10- and 100-msec, 500-Hz tones and octave-band noise bursts presented in quiet and noise backgrounds. Threshold-duration functions were significantly steeper for infants than for adults under all experimental conditions, and did not differ in slope as a result of differences in either stimulus bandwidth or masking noise. In Experiment 2, thresholds for trains of brief 500-Hz tone pulses were examined in infant and adult subjects. Infant functions were adult-like for integration of multiple-pulse stimuli, suggesting that the traditional, long-term process of temporal summation is mature by 7 months of age. Differences between the present results and those previously obtained for 4-kHz stimuli appear to be consistent with the view that different mechanisms are involved in the detection of low- and high-frequency signals.
Berg
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KM
Institute for Advanced Study of the Communication Processes, University of Florida, Gainesville 32611.
Boswell
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AE
D000328:Adult; D001288:Attention; D001309:Auditory Threshold; D003216:Conditioning, Operant; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010898:Pitch Perception; D011571:Psychoacoustics; D002666:Psychology, Child; D012016:Reference Values; D013998:Time Perception