Nonspatial Features Reduce the Reliance on Sustained Spatial Auditory Attention.
Lia M Bonacci, Scott Bressler, Barbara G Shinn-Cunningham
PMID 33136638WHAT IT FOUND
When listeners hear competing sounds, they use location to pick the target stream initially.
However, if the sounds differ clearly in pitch, they stop relying on location to maintain attention. This means spatial brain signals fade even though the listener is still focused on the target.
Key findings
01Brain signals related to spatial attention (parietal alpha lateralization) were strong when participants first heard the cue indicating where to listen.
02During the task itself, spatial attention signals became weak or non-significant when the target and distractors had large differences in pitch.
03Spatial attention signals remained strong during the task only when pitch differences were small, forcing reliance on location.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study used a specific, artificial task with melodies separated by interaural time differences (ITDs) rather than realistic head-related transfer functions or complex speech. The spatial separation was held constant at ±100 μsec ITD; it is unclear if results would differ with larger or smaller spatial gaps. Participants were young adults with normal hearing, so findings may not apply to older adults or those with hearing loss who have degraded auditory representations. The study did not parametrically vary pitch and space, so it cannot determine the exact threshold at which listeners switch from spatial to non-spatial attention.
Declared interests
The authors declared no competing financial interests. The research was supported by the National Institutes of Health (N.I.H., Extramural).
The easy way to misread this
Do not assume that the absence of spatial brain signals means the listener is not paying attention. The study showed that attention was successfully maintained even when spatial signals faded, provided pitch cues were strong. The listener simply switched strategies.