title: One sound or two? Object-related negativity indexes echo perception.
abstract: The ability to isolate a single sound source among concurrent sources and reverberant energy is necessary for understanding the auditory world. The precedence effect describes a related experimental finding, that when presented with identical sounds from two locations with a short onset asynchrony (on the order of milliseconds), listeners report a single source with a location dominated by the lead sound. Single-cell recordings in multiple animal models have indicated that there are low-level mechanisms that may contribute to the precedence effect, yet psychophysical studies in humans have provided evidence that top-down cognitive processes have a great deal of influence on the perception of simulated echoes. In the present study, event-related potentials evoked by click pairs at and around listeners' echo thresholds indicate that perception of the lead and lag sound as individual sources elicits a negativity between 100 and 250 msec, previously termed the object-related negativity (ORN). Even for physically identical stimuli, the ORN is evident when listeners report hearing, as compared with not hearing, a second sound source. These results define a neural mechanism related to the conscious perception of multiple auditory objects.
authors.affiliation: Department of Psychology, University of Massachusetts, Amherst, Massachusetts 01003, USA. lsanders@psych.umass.edu
authors.forename: Lisa D
authors.initials: LD
authors.lastname: Sanders
authors.forename: Amy S
authors.initials: AS
authors.lastname: Joh
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Keen
authors.forename: Richard L
authors.initials: RL
authors.lastname: Freyman
mesh_terms: D000328:Adult; D001307:Auditory Perception; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D011601:Psychophysics