Reverberation and bottom-up cues in spatial selective auditory attention.

Abstract

Given multiple, competing speech streams, listeners can selectively attend to a desired stream using spatial cues made available by fine timing information arriving at the ears and passing to progressively higher regions of auditory processing. Reverberation smears fine temporal information needed for encoding important spatial cues, which may interfere with the ability to selectively attend to a target from a particular direction. To test this hypothesis, subjects were asked to focus spatial attention toward a location simulated directly in front of them and report a stream of digits from that location while ignoring two masker streams symmetrically positioned at 15 deg left and right. Three levels of reverberation were simulated to measure the influence of reverberant energy on performance. Results show that spatial selective attention degrades as reverberation increases and that overall performance varies dramatically from listener to listener in ways that are not predicted by age or memory span. Performance is highly correlated with absolute sensitivity to frequency modulation. Ongoing studies are exploring whether individual differences in performance on the spatial selection task are predicted by physiological frequency-following responses in the brain stem or by the process of aging.