Auditory Localization Aftereffects in the Median Plane: Elevation Shifts Induced by a Preceding Noise

Previous research has shown that a preceding sound can systematically influence the apparent position of a subsequent sound. Under certain conditions, the perceived location of the latter sound appears to be shifted away from the previous sound position. The present study examined this auditory localization aftereffect in the median plane. In a darkened anechoic environment, a distracter (broadband noise) was presented above, below, or in front of the listener's head. Immediately after the distracter, a 500-ms broadband target sound was presented at various elevations in the median plane. Listeners indicated the perceived target position by using a hand pointer. When the distracter and the target sound came from different elevations, the target appeared to be systematically shifted away from the distracter. This aftereffect occurred for long (3 s) and short (200 ms) distracter sounds with the exception that the short distracter sounds had no significant effect for targets above the upper and below the lower distracter locations. These results are consistent with earlier findings and with the hypothesis that the localization aftereffect is based on a kind of spatial auditory adaptation.