The effect of attention on adaptation produced by amplitude modulation (AM) was examined. In different experimental conditions, listeners’ AM detection thresholds for a 2 kHz test tone were measured after exposing them to an adapting sound that was presented simultaneously with speech distractors. Magnitude of an aftereffect, calculated as the elevation of the thresholds caused by adaptation, was smaller when the listeners shift attention away from the adaptor to the distractor voice than when they attended to the adaptor. The results suggest that the AM of unattended sounds may not be fully analyzed compared to that of attended sounds.