Identifying auditory events at a cocktail party: Principles of temporal integration and stream segregation.
ABSTRACT The question of how sequential sound elements are grouped into meaningful percepts has been within the focus of researchers for decades. This talk takes a new perspective by addressing how within-stream temporal integration occurs in the context of a cocktail party. In a noisy environment, the ability to identify specific events depends upon multiple processes: the overall segregation of sounds into streams as well as the within-stream integration of sequential sounds into meaningful units. This talk presents two studies that address the interaction of these two complex processes. Event-related potentials were used to determine effects of timing (Experiment 1) and of attention (Experiment 2) on the perception of within-stream sound events in multistream environments. Experiment 1 shows that within-stream temporal integration of sequential elements uses previously segregated streams as input. Experiment 2 shows that attention can override stimulus-driven processing biases to facilitate task demands. These results demonstrate different time courses for segregation of sounds into separate streams and for integration of sound elements into within-stream units. Thus, the findings suggest that different neural mechanisms interact in the perceptual organization of sequential sound elements.