Bottom-up and top-down influences on auditory scene analysis: Evidence from event-related brain potentials

The physiological processes underlying the segregation of concurrent sounds were investigated through the use of event-related brain potentials. The s timuli were complex sounds containing multiple harmonics, one of which coul d be mistuned so that it was no longer an integer multiple of the fundament al. Perception of concurrent auditory objects increased with degree of mist uning and was accompanied by negative and positive waves that peaked at 180 and 400 ms poststimulus, respectively. The negative wave, referred to as o bject-related negativity, was present during passive listening, but the pos itive wave was not. These findings indicate bottom-up and top-down influenc es during auditory scene analysis. Brain electrical source analyses showed that distinguishing simultaneous auditory objects involved a widely distrib uted neural network that included auditory cortices, the medial temporal lo be, and posterior association cortices.