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Acoustic modelling of cochlear implants
Dissertation (MEng (Bio-Engineering))--University of Pretoria, 2008.
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University of Pretoria
2013
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| _version_ | 1867613463287693312 |
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| access_status_str | Open Access |
| author2 | Hanekom, J.J. (Johannes Jurgens) |
| author_browse | Hanekom, J.J. (Johannes Jurgens) |
| author_facet | Hanekom, J.J. (Johannes Jurgens) |
| collection | Thesis |
| dc_rights_str_mv | © 2005 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MEng (Bio-Engineering))--University of Pretoria, 2008. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/27357 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:36:32.683Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/27357 Acoustic modelling of cochlear implants Hanekom, J.J. (Johannes Jurgens) upetd@up.ac.za Hanekom, Tania Conning, Mariette Confusion matrix Biophysics Speech-like noise Acoustic model Simulation Acoustic analysis UCTD Dissertation (MEng (Bio-Engineering))--University of Pretoria, 2008. High levels of speech recognition have been obtained with cochlear implant users in quiet conditions. In noisy environments, speech recognition deteriorates considerably, especially in speech-like noise. The aim of this study was to determine what underlies measured speech recognition in cochlear implantees, and furthermore, what underlies perception of speech in noise. Vowel and consonant recognition was determined in ten normal-hearing listeners using acoustic simulations. An acoustic model was developed in order to process vowels and consonants in quiet and noisy conditions; multi-talker babble and speech-like noise were added to the speech segments for the noisy conditions. A total of seven conditions were simulated acoustically; namely for recognition in quiet and as a function of signal-to-noise ratio (0 dB, 20 dB and 40 dB speech-like noise and 0 dB, 20 dB and 40 dB multi-talker babble). An eight- channel SPEAK processor was modelled and used to process the speech segments. A number of biophysical interactions between simulated nerve fibres and the cochlear implant were simulated by including models of these interactions in the acoustic model. Biophysical characteristics that were modelled included dynamic range compression and current spread in the cochlea. Recognition scores deteriorated with increasing noise levels, as expected. Vowel recognition was better than consonant recognition in general. In quiet conditions, the features transmitted most efficiently for recognition of speech segments were duration and F2 for vowels and burst and affrication for consonants. In noisy conditions, listeners mainly depended on the duration of vowels for recognition and the burst of consonants. As the SNR decreased, the number of features used to recognise speech segments also became fewer. This suggests that the addition of noise reduces the number of acoustic features available for recognition. Efforts to improve the transmission of important speech features m cochlear implants should improve recognition of speech in noisy conditions. Electrical, Electronic and Computer Engineering unrestricted 2013-09-07T11:15:56Z 2008-08-19 2013-09-07T11:15:56Z 2006-04-20 2008-08-19 2008-08-18 Dissertation Conning, M 2005, Acoustic modeling of cochlear implants, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/27357 > H860/ag http://hdl.handle.net/2263/27357 http://upetd.up.ac.za/thesis/available/etd-08182008-132242/ © 2005 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Confusion matrix Biophysics Speech-like noise Acoustic model Simulation Acoustic analysis UCTD Acoustic modelling of cochlear implants |
| title | Acoustic modelling of cochlear implants |
| title_full | Acoustic modelling of cochlear implants |
| title_fullStr | Acoustic modelling of cochlear implants |
| title_full_unstemmed | Acoustic modelling of cochlear implants |
| title_short | Acoustic modelling of cochlear implants |
| title_sort | acoustic modelling of cochlear implants |
| topic | Confusion matrix Biophysics Speech-like noise Acoustic model Simulation Acoustic analysis UCTD |
| url | http://hdl.handle.net/2263/27357 http://upetd.up.ac.za/thesis/available/etd-08182008-132242/ |