Academic literature on the topic 'Cochlear implant'

Bilateral cochlear implantation is accepted medical practice since 2008 in clinically suitable adults and children to enhance bilateral processing benefits. Bilateral implantation may lead to the restoration of some bilateral hearing advantages, such as improved speech recognition in noise, localisation, head shadow effect, summation, and squelch. The majority of the advantages stated in literature, though, are characteristic of the simultaneously implanted cochlear implant population. Simultaneous implantation is not yet a reality in South Africa due to funding constraints, therefore determining the bilateral processing abilities in sequentially implanted adults is essential. Determining bilateral processing benefits achievable with sequential implantation could result in evidence-based recommendations in terms of candidacy considerations, surgery protocols, motivations for medical aid funding for simultaneous cochlear implantation, and relevant measures to determine the bilateral processing benefit attainable. Furthermore, it might enhance audiologists‟ insight regarding post-implantation performance of sequentially implanted patients and enable them to counsel prospective candidates realistically. The aaim of this study was to determine the bilateral benefit attained by sequentially implanted adults. A quantitative, cross-sectional research approach was followed in a one group post-test-only exploratory research design. A purposive convenient sampling method with specified selection criteria was used to select 11 adult clients of an established cochlear implant programme in Pretoria. Tests of sound localisation in the horizontal plane and speech perception in noise were performed. During the test of sound localisation, performance with only the first or only the second implant was found to be very similar. For the majority of participants the second cochlear implant (CI 2) was the superior performing implant during xviii speech perception in noise testing, in spatially separated speech and noise conditions where noise was directed to the first implant, as well as in spatially coincident speech and noise. A statistical significant bilateral benefit (p < 0.05) was attained by sequentially implanted adults for sound localisation. A bilateral benefit for speech perception in noise was observed when noise was directed to the first implant and in the diotic listening condition with average benefits of 1.69 dB and 0.78 dB, respectively. It was not statistically significant (p > 0.05), however, and was smaller than bilateral benefit values achieved by simultaneously implanted adults in previous studies. The head shadow effect at 180° was found to be the strongest and most robust bilateral spatial benefit. Squelch and summation benefit values ranged from negative values to 2 dB and 6 dB, respectively. This corresponded with values found in previous studies. The improvement in speech perception in spatially distinct speech and noise from adding the ear with a better SNR (signal to noise ratio) indicated that the contribution of CI 2 seems to be greater than that of CI 1 for bilateral spatial benefit. It can be concluded that adults with sequential implants may achieve some extent of bilateral benefit even with many years of unilateral implant use, when speech processors differ, when the second implant is done ≥ 10 years after the first implant, and in cases of prelingual deafness. A key benefit of sequential implantation appears to be related to the advantage of having hearing on both sides so that the ear with the more favourable environmental signalto-noise ratio is always available. AFRIKAANS : Bilaterale kogleêre inplanting is sedert 2008 aanvaarde mediese praktyk vir klinies geskikte volwassenes en kinders, ten einde bilaterale prosesseringsvoordeel te verhoog. Bilaterale inplanting kan lei tot die herstel van sommige van die voordele van bilaterale gehoor, soos verbeterde spraakherkenning in lawaai, klanklokalisering, die kopskadueffek, sommering en selektiewe onderdrukking (“squelch”). Die meeste van die voordele wat in die literatuur bespreek word, is egter kenmerkend van dié persone by wie twee kogleêre inplantings gelyktydig gedoen is. Gelyktydige inplanting is as gevolg van beperkte befondsing nog nie in Suid-Afrika 'n werklikheid nie, daarom is dit noodsaaklik om te bepaal watter bilaterale prosesseringsvoordele by opeenvolgend-geïnplanteerde volwassenes voorkom. Die bepaling van watter bilaterale prosesseringsvoordele met opeenvolgende inplanting bereik kan word, sou kon lei tot getuienis-gebaseerde aanbevelings met betrekking tot besluite oor die geskiktheid van kandidate, protokol vir sjirurgie, motiverings vir die befondsing van gelyktydige kogleêre inplantings deur mediese voorsorgfondse, en toepaslike maatstawwe om te bepaal watter mate van bilaterale prosesseringsvoordeel haalbaar sou wees. Dit sou verder oudioloë se insig kon verbreed met betrekking tot die na-operatiewe prestasie van opeenvolgend-geïnplanteerde persone en hulle sodoende in staat stel om voornemende kandidate van realistiese raad te bedien. Die doel van hierdie studie was om te bepaal wat die bilaterale prosesseringsvoordele is wat deur opeenvolgend-geïnplanteerde volwassenes verkry kan word. 'n Kwantitatiewe navorsingsbenadering met 'n dwarsprofiel van „n enkelgroep is gevolg, met 'n post-toets verkennende navorsingsontwerp. 'n Doelgerigte gerieflikheidssteekproef met 'n gespesifiseerde seleksiekriteria is gebruik om 11 volwasse kliënte van 'n gevestigde kogleêre inplantprogram in Pretoria te selekteer. Klanklokalisering in die horisontale vlak en die waarneming van spraak in lawaai is getoets. Tydens die toets vir klanklokalisering is gevind dat prestasie met slegs die eerste of slegs die tweede inplanting soortgelyk was. Vir die meeste deelnemers aan die studie het die tweede kogleêre inplanting (KI 2) die beste prestasie gelewer tydens spraakwaarneming in lawaai, in omstandighede waar spraak en lawaai ruimtelik geskei is en die lawaai op die eerste inplanting gerig is, asook in omstandighede waar spraak en lawaai ruimtelik saamvoorkomend aangebied is. 'n Statisties beduidende bilaterale voordeel (p < 0.05) is deur opeenvolgend-geïnplanteerde volwassenes vir klanklokalisering behaal. 'n Bilaterale voordeel vir spraakwaarneming in lawaai is waargeneem waar lawaai op die eerste inplanting gerig is en ook in diotiese luistertoestande, met 'n gemiddelde voordeel van 1.69 dB en 0.78 dB, onderskeidelik. Dit was egter nie statisties beduidend nie en was ook kleiner as die bilaterale voordeelwaardes wat in vorige studies deur gelyktydig-geïnplanteerde volwassenes behaal is. Die kopskadu-effek by 180° was die sterkste en mees robuuste bilaterale ruimtelike voordeel. Voordeelwaardes vir selektiewe onderdrukking en sommering het gewissel van negatiewe waardes tot 2 dB en 6 dB onderskeidelik. Dit stem ooreen met waardes wat in vorige studies gevind is. Die verbetering in spraakwaarneming in ruimtelik geskeide spraak en lawaai wat verkry is deur die oor met 'n beter STR (sein-tot-ruis ratio) by te voeg, het daarop gedui dat die bydrae van KI 2 tot bilaterale ruimtelike voordeel waarskynlik groter as die bydrae van KI 1 is. Die gevolgtrekking kan gemaak word dat volwassenes met opeenvolgende inplantings 'n mate van bilaterale voordeel verkry selfs na vele jare van unilaterale inplantingsgebruik, wanneer die spraakprosesseerders in die twee inplantings van mekaar verskil, wanneer die tweede inplanting ≥ 10 jaar na die eerste plaasvind, en in gevalle van prelinguale doofheid. 'n Sleutelvoordeel van opeenvolgende inplanting hou klaarblyklik verband met die voordeel van gehoor aan albei kante te hê sodat die oor met die gunstigste sein-tot-lawaai ratio altyd beskikbaar is.<br>Dissertation (MCommunication Pathology)--University of Pretoria, 2012.<br>Speech-Language Pathology and Audiology<br>Unrestricted

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.<br>Includes bibliographical references (p. 171-179).<br>Cochlear implants, or bionic ears, restore hearing to the profoundly deaf by bypassing missing inner-ear hair cells in the cochlea and electrically stimulating the auditory nerve. For miniaturized cochlear implants, including behind-the-ear (BTE) models, power consumption is the chief factor in determining cost and patient convenience. This thesis reports on the design of a low-power bionic ear system by addressing three critical signal and power processing subsystems in low-cost CMOS ICs. First, the design of a low-power current-mode front-end for subminiature microphones demonstrates 78dB dynamic range performance with attention to RF noise and supply immunity. Second, hearing-impaired patients need strategies that decide intelligently between listening conditions in speech or noise. This work describes an automatic gain control (AGC) design which uses programmable hybrid analog-digital current-mode feedback to implement a dual-loop strategy, a well-known algorithm for speech in noisy environments. The AGC exhibits level-invariant. stability, programmable time constants and consumes less than 36pW. Third, a feedback-loop technique is explored for analyzing and designing RF power links for transcutaneous bionic ear systems.<br>(cont.) Using feedback tools to minimize algebraic manipulations, this work demonstrates conditions for optimal voltage and power transfer functions. This theory is applied to a bionic implant system designed for load power consumptions in the 1mW - 10mW range, a low-power regime not significantly explored in prior designs. Link efficiencies of 74% and 54% at 1-mm and 10-mm coil separations, respectively, are measured, in good agreement with theoretical predictions. A full cochlear implant system with signal and power processing is explored incorporating the front-end, AGC, and RF power link, as well as analog signal processing channels. This design uses channel data to feedforward program the just-needed electrode power level. My implant system consumes 3mW of power for all audio processing and a stimulation power of 1mW. A fixed-power version of this system dissipates 2.2mW for 1mW of internal stimulation power. As many commercial systems with similar specifications consume 40mW - 80mW, this effort promises a significant reduction in cochlear implant power consumption and cost.<br>by Michael W. Baker.<br>Ph.D.

This thesis describes a series of experiments investigating both sequential and concurrent auditory grouping in implant listeners. Some grouping cues used by normal-hearing listeners should also be available to implant listeners, while others (e.g. fundamental frequency) are unlikely to be useful. As poor spectral resolution may also limit implant listeners’ performance, the spread of excitation in the cochlea was assessed using Neural Response Telemetry (NRT) and the results were related to those of the perceptual tasks. Experiment 1 evaluated sequential segregation of alternating tone sequences; no effect of rate or evidence of perceptual ambiguity was found, suggesting that automatic stream segregation had not occurred. Experiment 2 was an electrode pitch-ranking task; some relationship was found between pitch-ranking judgements (especially confidence scores) and reported segregation. Experiment 3 used a temporal discrimination task; this also failed to provide evidence of automatic stream segregation, because no interaction was found between the effects of sequence length and electrode separation. Experiment 4 explored schema-based grouping using interleaved melody discrimination; listeners were not able to segregate targets and distractors based on pitch differences, unless accompanied by substantial level differences. Experiment 5 evaluated concurrent segregation in a task requiring the detection of level changes in individual components of a complex tone. Generally, large changes were needed and abrupt changes were no easier to detect than gradual ones. In experiment 6, NRT testing confirmed substantially overlapping simulation by intracochlear electrodes. Overall, little or no evidence of auditory grouping by implant listeners was found.

The timbre perception of cochlear implantees (CI) is poor compared to normal hearing (NH) listeners. The cues that are normally transmitted to NH listeners may be less salient or even absent for CI users. From the literature, two spectral (brightness (Tb) and irregularity (IRR)) and two temporal timbre parameters (log rise-time (LRT) and sustain/decay (S/D) parameter (n)) have been identified as important timbre parameters. Each of these parameters was extracted for a set of thirteen instruments. Sounds could be resynthesized according to the specific timbre parameter set. The variation of loudness, pitch and perceived duration as functions of the timbre parameters were investigated to provide systematic balancing methods. The just-noticeable differences (JNDs) were obtained for each of the parameters for thirteen instruments for NH listeners and a reduced instrument set of nine instruments for the CI users using a 1-up, 2-down, two-alternative, forced choice procedure. From the JNDs, predicted confusion matrices were constructed. From the confusion matrices, a feature information transmission analysis (FITA) indicated the salience of each of the parameters and NH and CI results could be compared.<br>Dissertation (MEng)--University of Pretoria, 2011.<br>Electrical, Electronic and Computer Engineering<br>MEng<br>Unrestricted

Background to the study: Cochlear implants (CI) can help to suppress tinnitus and often make existing tinnitus more bearable. However, a number of patients still suffer from tinnitus afterwards. In some cases the implantation makes existing tinnitus worse, or tinnitus may occur as a result of cochlear implantation. Because of the inconclusive aetiology of tinnitus it is difficult to treat its effects. So far, one of the most popular treatments for tinnitus is the widely used Cognitive Behavioural Therapy (CBT), which aims to influence dysfunctional emotions, behaviours and cognitions though a goal-orientated, systematic procedure. CBT aims to minimize the side-effects of tinnitus and help to manage it in a more efficient way. CBT has been investigated in several studies and shows promising results in reducing the debilitating effect of tinnitus. CBT has not yet been used specifically for, or investigated in, relation to treating CI users suffering from tinnitus. Aims and outline of the study: Our research aimed to investigate CBT’s effectiveness for cochlear implant users. Using a randomized control trial, we investigated whether two-hour Tinnitus Workshops for the control group were as equally as effective as CBT for the research group. We also explored if either type of treatment for cochlear implant users needed any modifications to make them more suitable for this group of tinnitus sufferers. Using Open Questions, we investigated tinnitus in cochlear implant users. We analysed the Open Questions from both groups, creating a profile of a typical cochlear implant user who suffers from tinnitus, and we also explored whether both interventions (Tinnitus Workshop or CBT) were suitable for this kind of patient. Data was gathered, pre- and post-interventions, by questionnaires; these were Tinnitus Questionnaires (TQ), Visual Analogue Scale (VAS), Quality of Life Short Form 36 Health Survey (SF-36) and Hospital Anxiety and Depression Scale (HADS). Results: In the control group, we found no significant differences between the TQ scores pre- and post-intervention. VAS scores post-intervention were lower than pre-intervention, indicating some improvement in individual tinnitus perception; however, the difference was not significant. In the research group, we found small, but not significant, differences in both TQ pre- and post-intervention (z =1.83, p>.05) and in VAS (z=0.14, p>.05). No significant differences were found between the control and the research group pre- and post-intervention. Conclusions: The questionnaires used in this study, such as TQ or VAS, showed a decrease in general tinnitus distress, but a larger-sized sample group may be needed for greater statistical certainty. The results from the Open Questions showed that cochlear implant users were affected by tinnitus in a similar way to non-cochlear implant users. Overall, both interventions need further, small modifications and adjustments to their protocols in order to be more effective for this type of tinnitus sufferer.