Perception of dynamic multi-speaker auditory scenes under different modes of attention.

Attention is not monolithic; rather, it operates in multiple forms to facilitate efficient cognitive processing. In the auditory domain, attention enables the prioritization of relevant sounds in an auditory scene and can be either attracted by elements in the scene in a bottom-up fashion or directed towards features, objects, or the entire scene in a top-down fashion. How these modes of attention interact and whether their neural underpinnings are distinct remains unclear. In this work, we investigate the perceptual and neural correlates of different attentional modes in a controlled "cocktail party" paradigm, where listeners listen to the same stimuli and attend to either a spatial location (operationalized here as a feature-based auditory attribute), a speaker (object-based), or the entire scene (global or free-listening) while detecting deviations in pitch of a voice in the scene. Our findings indicate that object-based attention is more perceptually effective than feature-based or global attention. Furthermore, object-based and spatial-based attention engage distinct neural mechanisms and are differentially modulated by bottom-up salience. Notably, while bottom-up salience aids in the initial segregation of auditory objects, it plays a reduced role in object tracking once attention has been voluntarily allocated. In addition, decoding the stimulus envelope from the EEG data revealed a source-sampling scheme in the global attention mode that is not present in the object or spatial modes. Overall, the study shows that the perception of the same acoustic scene differs according to the listening task, guided by an interaction between top-down and bottom-up processes.