Estimating the contribution of non-sensory factors to infant-adult differences in behavioral thresholds.
Estimates of behavioral thresholds of infants are elevated relative to those of adults. Explanations for the differences include auditory sensory factors and non-sensory factors, but no direct estimates of the relative contributions of these two factors have been made. In this investigation, thresholds in quiet and in increasing levels of a masking noise for a 1 kHz tone, in infants 8 to 11 months old and in adults, were determined. The infant-adult differences in unmasked threshold was compared to the infant-adult difference in an estimate of the minimum masking level (MML) that was derived from the masking data. The intensity level of a masking noise at which masking begins is assumed to be independent of the non-sensory factors that impact on the threshold value itself. Therefore, it is reasoned that the infant-adult difference in MML reflects more closely differences in auditory sensory factors than does the infant-adult difference in unmasked threshold. In the region of 1 kHz, the infant-adult difference in behavioral threshold was 12 dB and the infant-adult difference in MML was 8 dB. Therefore, according to our assumptions, 8 dB of the infant-adult difference in unmasked threshold is accounted for by sensory factors and the remaining 4 dB must be attributable to non-sensory factors.
Nozza
R J
RJ
Department of Communication Sciences and Disorders, University of Georgia, Athens 30602-7152, USA. bnozza@moe.coe.uga.edu
D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology*; D001309:Auditory Threshold / Q000502:physiology*; D003198:Computer Simulation; D004424:Ear Canal / Q000502:physiology; D005260:Female; D006801:Humans; D007223:Infant; D018730:Infant Behavior; D008297:Male; D008954:Models, Biological; D010470:Perceptual Masking; D011597:Psychomotor Performance / Q000502:physiology*