Interhemispheric Auditory Cortical Synchronization in Asymmetric Hearing Loss.
Jolie L Chang, Ethan D Crawford, Abhishek S Bhutada and 8 others
PMID 33974786WHAT IT FOUND
Amplifying the poorer ear in asymmetric hearing loss restored normal brain timing between hemispheres and improved speech-in-noise scores in three subjects.
The brain's response to sound shifted back toward normal patterns over 12 months, suggesting the auditory system remains plastic in adults.
Key findings
01Interhemispheric brain response timing was significantly less asynchronous in people with asymmetric hearing loss compared to normal-hearing controls.
02Monaural amplification of the poorer ear reversed this synchrony, restoring normal interhemispheric timing over 12 months.
03Hearing in noise improved in two of three subjects who had measurable impairment at baseline after six months of amplification.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The longitudinal component involved only three subjects, which is too small to draw general conclusions about treatment efficacy. The study focused on the better ear for determining stimulus levels, which may have affected the accuracy of responses from the poorer ear. One subject had normal hearing in noise at baseline, so improvement could not be measured in that individual. The study did not include a control group for the longitudinal arm, so it is unclear if changes were due solely to the hearing aid or other factors.
Declared interests
Funding was provided by the Department of Defense, NIH, Triological Society, Hearing Research, Inc, and the Coleman Memorial Fund. The authors declared no conflicts of interest.
The easy way to misread this
Do not interpret the improvement in the three subjects as proof that hearing aids work for everyone with asymmetric hearing loss. The sample size is extremely small, and one subject showed no functional improvement because they did not have a deficit to begin with.