Effect of Place-Based Versus Default Mapping Procedures on Masked Speech Recognition: Simulations of Cochlear Implant Alone and Electric-Acoustic Stimulation.
Margaret T Dillon, Brendan P O'Connell, Michael W Canfarotta and 2 others
PMID 35394798WHAT IT FOUND
Normal-hearing listeners identified sentences better in noise when simulated cochlear implant maps aligned frequencies to the cochlea's natural layout.
This held for both electric-only and hybrid acoustic-electric modes, though the study did not test actual implant users.
Key findings
01Place-based maps yielded significantly better sentence recognition in noise than default maps for both CI-alone and EAS simulations.
02The benefit of adding low-frequency acoustic information was similar for both spectrally shifted default maps and place-based maps.
03Simulations modeled a challenging case of a shallow-insertion 24-mm array, where default maps create large frequency-to-place mismatches.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Participants had normal hearing and no experience with vocoded speech, so results may not reflect the performance of actual CI recipients who have neural plasticity and acclimatization. The study modeled a single case of a 24-mm array with a shallow insertion angle, which represents an extreme mismatch scenario; results may not generalize to longer arrays or deeper insertions. Performance was assessed acutely, without accounting for the ability of listeners to acclimate to spectrally shifted maps over time. The simulations did not account for channel interactions or electric-on-acoustic masking, which are common in actual device use. Participants did not complete all conditions, limiting within-subject comparisons.
Declared interests
Funding was provided by the National Institute on Deafness and Other Communication Disorders and the University of North Carolina. Authors M.T.D. and E.B. are supported by a research grant from MED-EL Corporation. Author B.P.O. is a consultant for Advanced Bionics, MED-EL, and Johnson & Johnson.
The easy way to misread this
Do not assume place-based mapping is clinically superior for actual cochlear implant users. This study used normal-hearing listeners and computer simulations of a specific, challenging electrode insertion case. Actual implant users may acclimate to default maps over time, and the simulations did not account for neural factors like channel interaction that affect real-world performance.