Sound Localization in Real-Time Vocoded Cochlear-Implant Simulations With Normal-Hearing Listeners.
Sebastian A Ausili, Bradford Backus, Martijn J H Agterberg and 2 others
PMID 31088265WHAT IT FOUND
Simulating cochlear implants in normal-hearing listeners worsened sound localization.
Bilateral simulation made listeners point to fixed left or right spots, nearly abolished elevation, and slowed responses. Unilateral simulation still impaired the normal-hearing side.
Key findings
01With bilateral cochlear-implant simulation, normal-hearing listeners showed strongly impaired horizontal localization and tended to respond at fixed left or right locations.
02With bilateral simulation, elevation localization was nearly impossible across the horizontal plane.
03With one ear simulated and one normal-hearing ear, localization was closer to normal on the normal-hearing side than on the simulated side, but elevation performance was still reduced.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study tested normal-hearing listeners using an acoustic simulator, not cochlear implant users, so it does not show what actual implant recipients do over time. Listeners were tested acutely, immediately after the simulation was introduced, so long-term learning or adaptation was not measured. The sounds were brief noise bursts, not speech or everyday environmental sounds, and the room had no competing sounds or reflections. Only 11 listeners participated, and only 7 completed the unilateral condition. The simulation combined microphone position and processor effects; it did not separate how much each contributed. Acoustic vocoder output differs from electrical cochlear-implant hearing, which can include current spread, degraded auditory nerve function, and smaller electrical dynamic range.
Declared interests
The supplied text names FP7 People: Marie-Curie Actions as funder and says the Oticon Medical Research Platform vocoder was provided by Oticon Medical.
The easy way to misread this
Do not conclude that cochlear implant users cannot localize sounds because of this simulation. It tested normal-hearing listeners acutely with brief noise bursts, not implant users, speech, or everyday listening conditions.