Le 13 septembre 2006, à 17 heures. ENS, salle des Résistants.
Antje Ihlefeld, Auditory Neuroscience Lab, Hearing Research Center, Boston University
"The impact of spatial attention on selective and divided listening"
Imagine yourself at a crowded party, trying to understand words uttered by your attractive new acquaintance. You are facing the challenge of extracting syllables out of a cacophony of background sounds and grouping them properly across time. Spatial auditory cues can help in segmenting and grouping a sound mixture into auditory objects. Many of the factors that contribute to this spatial separation advantage (acoustic target-to-masker ratio effects at the better ear, low-level binaural processing) may not require active spatial attention from the listener. However, when informational masking is the primary form of interference, differences in target and masker attributes such as perceived location, timbre, or other cues appear to improve performance because they enable a listener to actively focus attention on the target in a top-down manner. This talk will present findings from three human psychophysical studies that measured speech intelligibility in a two-talker setting. Our results confirm that subjects can direct attention to spatial and non-spatial attributes to select an auditory object, just as for visual objects. Importantly, we also show that spatial separation strengthens auditory object formation whether or not listeners are attending to space. Finally, we demonstrate that a priori knowledge about the spatial configuration of the sources affects spatial unmasking in selective and divided listening in stimulus conditions that are dominated by informational masking. These results demonstrate that perceptual organization of sound depends directly on spatial information, not just on spectrotemporal structure, a finding with important practical implications.
ENS, Salle des Résistants : Ecole Normale Supérieure, _45_ rue d'Ulm, 75005 Paris [plan]