Interactions between attention and auditory scene analysis

Do auditory objects form automatically, or only when a listener focuses attention on a sound? This review argues that the question is ill posed—that both are simultaneously correct. Intuition suggests that the processes of source segregation and attention happen sequentially: first segregation parses a complex scene into constituent objects, and then selection pulls out an important sound to be analyzed in detail. But, rather than a processing hierarchy in which object formation occurs first, followed by selection, auditory scene analysis and attention interact in a heterarchy: formation and selection influence one another, feed back upon each other, and are not easily separable in terms of either how they are implemented in the brain or how their effects can be measured. There is not one particular site in the auditory pathway where objects “first appear;” instead, an object-based representation emerges gradually and imperfectly from the auditory nerve through the brainstem and midbrain to the various divisions of the cortex. Similarly, attentional selection accrues at every stage as one moves from the ear to the cortex. This talk will review examples from perceptual and physiological experiments supporting the idea that attention and object formation interact heterarchical.