A Comparison of Pure Tone Auditory Thresholds in Human Infants and Adults.

Pure tone auditory thresholds for frequencies from .250 to 8.0 kHz were obtained from 277-to-11-month-old human infants and nine adults using a go-no-go operant head-turning technique combined with an adaptive staircase (tracking) discrimination procedure. New methods were devised for maintaining infants under stimulus control during threshold testing through the use of randomly interleaved "probe" and "catch" trials. Reliable threshold data were obtained from every infant studied, and identical threshold criteria were applied to infants and adults alike. Although infant thresholds were 17-27 dB higher than those of adults, infant inter-subject variability was no greater than that of adults. Adult audiograms were nearly flat between frequencies of .500 and 8.0 kHz with sensitivity ranging between 7 and 14 dB SPL. Infant audiograms were flat between frequencies of .500 and 4.0 kHz, with sensitivity ranging between 30 and 36 dB SPL. The most sensitive frequency for infants was 8.0 kHz (25 dB SPL).