Effect of Signal Duration on the Auditory Sensitivity of Humans and Monkeys (Macaca mulatta)

Abstract

The changes in absolute sensitivity of monkeys and humans are compared as a function of signal duration. Pure tone thresholds, both monaural and binaural, were obtained from the two monkeys (Macaca mulatta) using a single‐lever, go no go, shock‐avoidance conditioning procedure. The monaural thresholds for the seven women were determined under similar acoustic and behavioral conditions. The signal durations sampled were from 10 to 1500 msec at frequencies between 250 and 8000 cps. The results show that (1) the rate of change in threshold as a function of signal duration is linear with a slope dependent upon frequency—slope is highest below 1000 cps for both humans and monkeys; (2) although the integration rates for humans and monkeys are nearly identical at 2000 and 4000 cps, they differ at the frequency extremes. An attempt is made to show that these results do not depend upon the critical‐ratio differences of the ears but are related to long‐term sensitivity.