Listening Effort Measured With Pupillometry in Cochlear Implant Users Depends on Sound Level, But Not on the Signal to Noise Ratio When Using the Matrix Test.
Hendrik Christiaan Stronks, Annemijn Laura Tops, Kwong Wing Quach and 2 others
PMID 38886888WHAT IT FOUND
For cochlear implant users, pupil dilation did not change with speech difficulty, making this physiological measure unreliable for assessing listening effort in this group.
Subjective ratings did change with difficulty, but likely reflected performance rather than effort alone.
Key findings
01Pupil dilation in cochlear implant users did not significantly depend on the signal-to-noise ratio, unlike in normal-hearing listeners.
02Subjective ratings of listening effort changed significantly with difficulty for both groups, but the authors suggest these ratings may have reflected perceived performance rather than mental exertion.
03The study found that the Matrix test may not be a feasible tool for measuring within-group effects of listening difficulty on pupil dilation in cochlear implant users.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The cochlear implant group was substantially older (mean 64.3 years) than the control group (mean 33.1 years), which affects pupil size and cognitive processing. The study used a small sample size and was a pilot, limiting the generalizability of the null findings for pupil dilation. Participants with eye disorders were included, which could affect pupillometry results, though the authors state their responses appeared normal. The subjective rating task lacked a fixed anchor, which may have led to inconsistent use of the scale across tests. The Matrix test sentences lack semantic context, which may not reflect real-world listening effort where context helps reduce cognitive load.
Declared interests
The study was supported by funds from Advanced Bionics, LLC, the manufacturer of the cochlear implant devices used by the participants.
The easy way to misread this
Do not conclude that cochlear implant users experience no change in listening effort with noise. The null finding for pupil dilation likely reflects a limitation of the measurement tool or test design in this population, not an absence of effort. Subjective ratings increased with difficulty, but may have tracked performance accuracy rather than mental strain.