Abstract:

The precedence effect is a compelling auditory illusion which is thought to negotiate competition for perception and localization between the direct sound and its reflections. Three perceptual phenomena that have been related to the precedence effect are known to occur: (1) the two sounds are fused into one auditory event (fusion); (2) the perceived location of the fused auditory event is dominated by the leading source (localization dominance); and (3) directional information from the lagging source is inaccessible (discrimination suppression). Performance was measured on the above tasks under both binaural and monaural conditions, in both the azimuthal and median-sagittal planes, and in listeners with profound monaural deafness. Results suggest that: (1) Fusion occurs at similar delays under monaural and binaural conditions; (2) discrimination suppression is strong under binaural conditions but weak or absent under monaural conditions; (3) localization dominance is similar in the azimuthal and median-sagittal planes. It is tentatively concluded that the precedence effect may not be mediated solely by binaural circuits, but that monaural pathways may be involved as well. [Work supported by NIH Grant Nos. DC02692 and DC00100.]