The role of innate and attentional mechanisms in parsing complex acoustic scenes: A neural and behavioral study.

Abstract

The mechanisms by which a complex auditory scene is parsed into coherent objects depend on poorly understood interactions between task-driven and stimulus-driven attentional processes. We use a simultaneous psychophysical-neurophysiological experimental paradigm to manipulate human listeners attention to different features of auditory scenes. In a series of experiments, our findings reveal a role of attention in enhancing the sustained neural representation of the foreground. This enhancement, in both power and phase coherence, originates in auditory cortex, occurs exclusively at the frequency of the target rhythm, and is only revealed when contrasting two attentional states that direct subjects focus to different features of the acoustic scene. It also interacts with innate processes of the auditory system, particularly its differential sensitivity to temporal dynamics of sounds. These results have substantial implications for models of foreground/background organization and mechanisms mediating auditory object formation.