Effects of Cochlear Implantation on Binaural Hearing in Adults With Unilateral Hearing Loss.
Emily Buss, Margaret T Dillon, Meredith A Rooth and 5 others
PMID 29732951WHAT IT FOUND
Adults with acquired unilateral hearing loss had better localization and better speech-in-noise scores after a cochlear implant program that included fitting, loudness matching, and aural rehabilitation, but not when the masker was on the implant side.
Key findings
01All 20 listeners had lower localization error in the CI condition than in the preoperative unaided condition.
02When the masker was on the normal-hearing side, masked sentence scores improved by an average of 36 percentage points from preoperative unaided testing to the 12-month CI condition.
03When the masker was on the CI side, masked sentence scores did not significantly improve; mean performance worsened by a nonsignificant 1.6 percentage points.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The implant group had only 20 participants, so individual variation could still be large. The normal-hearing comparison group was tested after the main study, so it was not a concurrent control group. Ten of the 20 normal-hearing controls had at least one threshold above 20 dB HL, so the control group was not uniformly normal hearing. The study followed participants for 12 months, so it cannot tell whether true binaural benefit might appear later. When the masker was on the implant side, some scores were close to 100% correct, which can limit detection of further improvement. The study included adults with acquired hearing loss and duration of loss of 10 years or less, so it does not address congenital or long-standing unilateral hearing loss.
Declared interests
MED-EL Corporation funded the work. CI recipients received their implant, surgery, two external speech processors, and batteries, and normal-hearing controls were paid $15/hr.
The easy way to misread this
Do not conclude that the cochlear implant alone restored normal binaural hearing. The participants also received device fitting, loudness matching, and aural rehabilitation, and the study cannot separate their contribution. In addition, there was no significant improvement when the masker was on the implant side, and implant users remained below normal-hearing controls on some tasks.