Effect of an auditory static distractor on the perception of an auditory moving target.

It is known that listeners lose the ability to discriminate the direction of motion of a revolving sound (clockwise vs counterclockwise) beyond a critical velocity ["the upper limit (UL)"], likely due to degraded front-back discrimination. Little is known about how this ability is affected by simultaneously present distractor sounds, despite the real-life importance of tracking moving sounds in the presence of distractors. We hypothesized that the presence of a static distractor sound would impair the perception of moving target sounds and reduce the UL and show that this is indeed the case. A distractor on the right was as effective as a distractor at the front in reducing the UL, despite the likely importance of resolving front-back confusions. By manipulating the spectral content of both the target and distractor, we found that the UL was significantly reduced only when the distractor spectrally overlaps with the target in the frequency range relevant for front-back discrimination. Our findings form the first steps toward a better understanding of the tracking of multiple sounds in the presence of distractors.