Fráter, Attila;
(2020)
Effects of electrical stimulation by cochlear implants on residual acoustic hearing.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
The objective of the project is the investigation of the mechanical changes and acousticelectric interactions in the cochlea with an implanted cochlear prosthesis to aid stimulation strategy design and propose techniques for detecting those interactions in users of cochlear implants (CI) with residual hearing, benefitting from electro acoustic stimulation (EAS) strategies. The effects of a CI electrode, inserted into the scala tympani, on the travelling wave are investigated by a modelling study. A three-dimensional finite element box model of the cochlea with an inserted CI is implemented and the changes in the travelling wave due to the CI electrode are examined while varying the parameters of the implant and its location. Attenuation and basal shift of the travelling wave peak was minimal under conditions where the electrode was not in the region of the travelling wave peak. Acoustic-electric interactions in the hearing cochlea are explored via in vivo physiology studies. A first set of experiments were conducted to establish a link between the electrophonic response and the electrically evoked otoacoustic emissions (EEOAE). Indications for a possible connection were found. A second set of experiments were carried out to investigate the interaction between electrophonic and acoustic response. A beating phenomenon between the electrophonic response and an acoustic pure tone evoked response was shown and, additionally, a modulation of the direct electric response due to the acoustic stimulus was revealed. Findings of the modelling study may be considered for acoustic stimulation design in EAS CIs. Results of the electrophysiological studies point towards the application of EEOAEs and the beating phenomenon as non-invasive clinical tests to detect electrophonic response in humans. In addition, a diagnostic test is proposed to reveal the effect that acoustic stimulation might have on the direct electric stimulation that might produce unwanted distortion of the desired electric responses.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Effects of electrical stimulation by cochlear implants on residual acoustic hearing |
| Event: | UCL (University College London) |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2020. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10093514 |
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