Effect of Noise Reduction on Cortical Speech-in-Noise Processing and Its Variance due to Individual Noise Tolerance.
Subong Kim, Yu-Hsiang Wu, Hari M Bharadwaj and 1 others
PMID 34751679WHAT IT FOUND
Noise reduction improved speech understanding for listeners with low noise tolerance but worsened it for those with high tolerance.
Overall accuracy slightly decreased. Neural activity suggested reduced processing effort in difficult noise, but this did not translate to better behavioral performance for the group.
Key findings
01Participants with lower noise tolerance (indexed by neural signal-to-noise ratio) showed improved speech-in-noise accuracy with noise reduction, while those with higher tolerance showed no improvement or deterioration.
02Across all participants, noise reduction caused a significant but slight decrease in behavioral accuracy compared to no noise reduction.
03In the most difficult listening condition, noise reduction increased activity in the supramarginal gyrus and decreased activity in the inferior frontal gyrus, suggesting more efficient processing despite no overall behavioral gain.
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 normal-hearing young adults, so results may not generalize to older adults or hearing aid users with hearing loss. The noise reduction algorithm was simulated in software, not delivered through actual hearing aids, which may have different processing characteristics. The study used single words, not continuous speech or sentences, which may not reflect real-world listening. Behavioral accuracy decreased overall, so the clinical benefit of the observed neural changes is unclear.
The easy way to misread this
Do not assume noise reduction improves speech understanding for all patients. In this study, overall accuracy slightly decreased with noise reduction, and only patients with low noise tolerance benefited. Patients with high noise tolerance may experience worse performance due to speech distortions introduced by the algorithm.