Perstimulatory suprathreshold adaptation was measured in 38 normal adult persons between 250 and 6000 Hz at 20, 40, 60, and 80 dB SL. In the experimental ear, the continuous stimulus had a constant intensity. In the control ear, the adjustable balancing stimulus had a duration of 200 msec with a silent interval of similar length. Adaptation increased at all frequencies as a function of SL up to 60 dB, but testing at 80 dB brought no further increase. At low tones, adaptation was smaller than at high frequencies. There were large individual differences; 5% showed no adaptation at all, 45% a very rapid growth, and 50% a slower adaptation reaching a maximum in212–3 min. Average adaptation was 30 dB at the high frequencies. In children, the same test generally revealed no adaptation at all; in old age, adaptation was comparable to the normal adult group.