Place-based mapping with electric-acoustic stimulation
Public Deposited- Creator
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Dillon, Margaret
- School of Medicine, Department of Allied Health Sciences, Division of Speech and Hearing Sciences
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Dillon, Margaret
- Abstract
- The goals of this dissertation were to understand the influence of electric frequency-to-place mismatches on the speech recognition of listeners of electric-acoustic stimulation (EAS) and whether listeners would experience better speech recognition with maps derived from a strict place-based mapping as compared to alternative mapping procedures. Current default EAS mapping procedures do not account for the individual variation in electrode array placement relative to cochlear tonotopicity, resulting in electric frequency-to-place mismatches. The strict place-based mapping procedure assigns the electric filter frequencies to match the cochlear place frequencies for electrodes in the low-to-mid frequency region and distributes the remaining high-frequency information across electrodes in the basal region. The rationales for this procedure are that eliminating mismatches will improve speech recognition since 1) critical speech information is provided by the mid-frequencies and 2) better spectral resolution of low-frequency cues may support better performance in noise. EAS simulation studies find acute masked speech recognition is significantly better with strict place-based maps as compared to maps with spectral shifts. For the present work, the first experiment evaluated the effectiveness of the strict place-based mapping procedure to an alternative full-frequency place-based mapping procedure using simulations of short electrode arrays at shallow angular insertion depths. Recipients of short arrays (e.g., ≤ 24 mm) may experience limited benefit with strict place-based maps since speech information below the frequency of the most apical electrode is discarded. The full-frequency place-based map would provide more low-frequency information yet present spectral shifts for the electrodes below the 1 kHz cochlear region. For the EAS simulations, performance with the strict map remained stable across cases, while performance with the full-frequency map improved with decreases in AID. The second experiment assessed the pattern of speech recognition acclimatization for EAS users listening with either a strict place-based map or default map. Poorer performance was observed for EAS users with larger magnitudes of electric mismatch out to 6-months post-activation. Taken together, the results from this dissertation suggest that eliminating electric frequency-to-place mismatches such as with the strict place-based mapping procedure supports better early speech recognition for EAS users than alternative mapping procedures.
- Date of publication
- 2022
- Keyword
- DOI
- Resource type
- Rights statement
- In Copyright - Educational Use Permitted
- Advisor
- Buss, Emily
- Chatterjee, Monita
- Firszt, Jill
- Grose, John
- Roush, Jackson
- Degree
- Doctor of Philosophy
- Degree granting institution
- University of North Carolina at Chapel Hill Graduate School
- Graduation year
- 2022
- Language
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