The effect of masker spatial uncertainty on sound localization

Abstract

Previous research from our laboratory has shown that uncertainty about the spatial location of a masking sound (randomly selected from 1 of 239 locations) can dramatically reduce localization accuracy for a simultaneous target relative to the case in which the masker location is known exactly. One possibility is that knowing the masker location enables the listener to establish a spatial attention filter at that location to suppress the masker and better localize the target. In this experiment, the level of masker spatial uncertainty was systematically varied across blocks by varying the number of possible masker locations (1, 2, 4, 8, or 239) and informing subjects about these possible locations prior to the start of each block. Localization errors were found to increase systematically in the left/right, front/back, and up/down dimensions as the number of potential masker locations increased; this effect was most prominent in the left/right dimension, where localization errors increased by nearly 30 degrees across conditions. Moreover, for a masker in a given location, errors generally increased across these levels of masker spatial uncertainty, consistent with the notion that there is a cost to distributing attention across multiple locations.