Pupil Responses of Adults With Traumatic Brain Injury During Processing of Speech in Noise.
Thomas Koelewijn, José A P van Haastrecht, Sophia E Kramer
PMID 30482105WHAT IT FOUND
Adults with brain injury but normal hearing scores understood speech in noise worse than age-matched normal-hearing adults.
They reported more effort, but pupil measures did not show greater peak effort. Visual language scores were similar.
Key findings
01Adults with TBI had normal hearing thresholds but worse speech-in-noise scores than normal-hearing adults (mean speech reception threshold -7.4 dB SNR versus -9.3 dB SNR; higher is worse).
02Peak pupil dilation did not differ significantly between TBI and normal-hearing adults, but within the TBI group worse speech-in-noise scores were associated with smaller peak pupil dilation.
03Participants with TBI rated their listening effort higher than normal-hearing and hearing-impaired adults, while their visual sentence completion scores were similar across groups.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The brain-injury group was small, with only 20 participants, and it mixed traumatic brain injury, stroke, and unspecified causes, so results cannot be separated by injury type. The comparison groups came from earlier studies and were not tested at the same time. The hearing-impaired comparison group was still older than the brain-injury group (54.2 versus 46.6 years). The study did not measure fatigue or distractibility directly, although the authors discuss them as possible explanations for the pupil pattern. It was a laboratory listening task, not a treatment study, so it does not show that any therapy will improve speech-in-noise listening. All participants had normal audiograms and were at least one year out from treatment, so the study did not test acute patients or people with hearing loss.
Declared interests
The article text does not report author conflicts. The publication types list non-U.S. government research support.
The easy way to misread this
Do not conclude that pupil size proves greater listening effort in adults with TBI. Peak pupil dilation was not significantly different between the TBI and normal-hearing groups (.16 mm versus .22 mm), and the authors say fatigue and distractibility explanations are speculative.