Spatial Release From Informational Masking: Evidence From Functional Near Infrared Spectroscopy.
Min Zhang, Yu-Lan Mary Ying, Antje Ihlefeld
PMID 30558491WHAT IT FOUND
Separating target and masker speech did not change frontal oxygen responses overall, but right frontal responses were stronger in the separated condition.
Actively listening to speech in a competing talker background raised frontal responses compared with passive listening.
Key findings
01Actively listening to intelligible speech in informational masking produced larger lateral frontal cortex oxygen responses than passive listening to scrambled speech.
02The spatial configuration comparison did not show an overall difference in lateral frontal cortex oxygen responses.
03Right lateral frontal cortex oxygen responses were stronger when target and masker were spatially separated than when colocated.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study tested 29 young normal-hearing adults (age 19 to 25), not children, older adults, or people with hearing loss, so it does not show how patients would respond. Behavioral speech performance was not reported in the main experiments because responses were inaccurately recorded due to a programming error; pilot data only state that detection was 90% correct or better. Experiment 2 had only 14 listeners in the group analysis, and one participant was excluded for falling asleep, so the spatial finding is small-sample and not a clinical effect. The spatial comparison did not show an overall difference; the reported spatial effect was a right-hemisphere interaction, which should not be treated as proof of spatial release. The outcome was a frontal cortex oxygen response, not speech intelligibility, hearing aid benefit, or cochlear implant outcome.
Declared interests
Funders named: Division of Chemical, Bioengineering, and Transport Systems and New Jersey Health Foundation.
The easy way to misread this
Do not conclude that spatial separation improves speech understanding or that fNIRS can clinically assess auditory attention. This study measured oxygen responses in normal-hearing adults, behavioral responses were not reported because of a programming error, and the spatial comparison did not show an overall difference; only the right-hemisphere interaction was significant.