Influence of Noise Reduction on Ocular Markers of Listening Effort in Hearing Aid Users in Darkness and Ambient Light.
Jessica Herrmann, Lorenz Fiedler, Dorothea Wendt and 3 others
PMID 40296543WHAT IT FOUND
Directional microphones with noise reduction improved speech understanding by about 35 percentage points in both light and dark.
But pupil dilation, an objective marker of listening effort, only decreased significantly in ambient light. This means lighting conditions must be controlled when using eye-tracking to assess effort.
Key findings
01Speech intelligibility improved substantially with the noise reduction algorithm in both lighting conditions.
02Pupil dilation decreased significantly with the algorithm only in ambient light, not in darkness.
03Age, hearing loss severity, and self-reported fatigue did not correlate with pupil dilation changes.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study relied on a small sample size of 26 participants. Participants had relatively low fatigue scores compared to other studies, which may explain the lack of correlation with pupil response. The interaction between sympathetic and parasympathetic nervous system activity in darkness could not be fully separated. Individual pupil saturation cannot be ruled out, though it is unlikely for most participants.
Declared interests
Funding was provided by the William Demant Foundation and the Institute of Acoustics at Technische Hochschule Lübeck. The authors declared no potential conflicts of interest.
The easy way to misread this
Do not conclude that noise reduction fails to reduce listening effort simply because pupil dilation does not change in darkness. The lack of effect in the dark is a measurement limitation related to how the autonomic nervous system responds to light, not evidence that the hearing aid setting is ineffective for the patient.