The Effects of Task Difficulty Predictability and Noise Reduction on Recall Performance and Pupil Dilation Responses.
Andreea Micula, Jerker Rönnberg, Lorenz Fiedler and 4 others
PMID 33859121WHAT IT FOUND
For hearing aid users, noise reduction improved recall of spoken words from 71.9% to 76.6%.
Telling participants the upcoming list length did not change recall, though it did alter pupil dilation. Noise reduction helps memory for speech even when the speech is already clear.
Key findings
01Noise reduction improved recall performance from 71.9% to 76.6% and word identification from 88.7% to 96.0%.
02Telling participants the upcoming list length did not change recall performance, but it did affect pupil dilation responses.
03Recall performance decreased as list length increased, from 93.0% for three sentences to 58.2% for seven sentences.
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 single hearing aid model and proprietary fitting software, so findings may not generalise to other devices or fitting rationales. The SWIR test uses a specific recall task (repeating and recalling last words of sentences) which may not capture all aspects of everyday conversational memory. One participant scored below the recommended MoCA cutoff of 23, though their performance was similar to others. The study was conducted in an anechoic chamber with controlled noise, which may not reflect complex real-world listening environments. The paper does not report the primary outcome as pre-registered or specified; the aims are described as three separate questions.
Declared interests
The authors have no conflicts of interest to declare. The study was supported by non-U.S. government funding.
The easy way to misread this
Do not assume that noise reduction improves recall by making speech easier to understand. In this study, all conditions were already at 95% intelligibility. The benefit came from freeing up cognitive resources for memory storage, not from improving audibility.