<p>This dissertation is about the first substantial restoration of human sense using a medical intervention. In particular, the development of the modern cochlear implant (CI) is described, with a focus on sound processors for CIs. As of October 2015, more than 460 thousand persons had each received a single CI on one side or bilateral CIs for both sides. More than 75 percent of users of the present-day devices use the telephone routinely, including conversations with previously unknown persons and with varying and unpredictable topics. That ability is a long trip indeed from severe or worse losses in hearing. The sound processors, in conjunction with multiple sites of highly-controlled electrical stimulation in the cochlea, made the trip possible.</p><p>Many methods and techniques were used in the described research, including but not limited to those of signal processing, electrical engineering, neuroscience, speech science, and hearing science. In addition, the results were the products of collaborative efforts, beginning in the late 1970s. For example, our teams at the Duke University Medical Center and the Research Triangle Institute worked closely with investigators at 27 other universities worldwide. </p><p>The most important outcome from the research was unprecedented levels of speech reception for users of CIs, which moved a previously experimental treatment into the mainstream of clinical practice.</p> / Dissertation

INTRODUÇÃO: Nos usuários de Implante Coclear (IC), o registro do potencial de ação composto do nervo auditivo evocado eletricamente (ECAP) representa o modo mais efetivo para se avaliar o estado do nervo auditivo em resposta ao estímulo elétrico e a interação entre o eletrodo e o tecido neural. Modificações nas respostas neurais ao longo do tempo têm implicação direta nos mapeamentos das crianças, principalmente durante os primeiros meses de uso do IC. OBJETIVO. Estudar o ECAP em crianças ao longo do primeiro ano de uso do IC. Por meio da Telemetria de Respostas Neurais, as características do ECAP foram analisadas em 13 crianças, implantadas com idades inferiores a três anos de idade. RESULTADOS. Durante o primeiro ano de uso do IC, houve aumento estatisticamente significante para a amplitude do pico N1, nos eletrodos basais, entre o segundo e o terceiro retorno. Não foram obtidas diferenças significantes para a latência do pico N1, para o slope e para o p-NRT, entre os retornos. Discretas alterações foram mais evidentes para os eletrodos basais. A análise entre os eletrodos mostrou que os eletrodos apicais apresentaram maiores amplitudes do N1 e valores do p-NRT, estatisticamente, inferiores aos limiares dos eletrodos apicais. Houve prevalência das respostas com morfologia do tipo Ia para os eletrodos E10, E15 e E20 e do tipo Ic para o eletrodo E5. No primeiro retorno, o tempo de recuperação do nervo auditivo de seu estado refratário foi, para a maioria dos sujeitos, igual a 1000 Mius para o E5, e igual a 2000 Mius para os eletrodos E5, E10 e E15. No terceiro retorno, o tempo de recuperação do E5 aumentou para 2000 Mius e, no E20, diminui para 1000 Mius, para a maioria dos sujeitos. A comparação entre os diferentes modelos revelou que o Implante Coclear N24 R (CS) apresentou as maiores amplitudes, os maiores slopes e as menores latências e menores valores de p-NRT. CONCLUSÃO. Ao longo do primeiro ano de uso do IC, a estimulação elétrica liberada pelos eletrodos intracocleares não causou alterações significativas às características do ECAP, exceto pelo aumento da amplitude do pico N1. / INTRODUCTION: In Cochlear Implant (CI) users, the recording of the electrically evoked compound action potential (ECAP) of the auditory nerve represents the most effective way to assess the auditory nerve in response to electrical stimulus and the interaction between the electrode and the neural tissue. Changes in neural responses, over time, have direct implication in mappings of children, mainly during the first months of CI use. OBJECTIVE: To study ECAP in children during the first year of CI use. Through Telemetry of Neural Responses, the ECAP characteristics have been analyzed in 13 children. The children who were implanted were younger than three years old. RESULTS: During the first year of CI use there was a significant statistical growth for the amplitude of N1 peak, in basal electrodes, between the second and third returns. There were not any significant differences obtained for N1 peak latency, neither for the slope nor for p-NRT, among the returns. The analysis among the electrodes has shown that the apical ones have presented higher N1 amplitudes and p-NRT values, statistically lower than the thresholds of apical electrodes. Responses with Ia type morphology have prevailed for electrodes E10, E15 and E20, and Ic type for electrode E5. In the first return, recovery time of the refractory state of the auditory nerve was in most subjects equals to 1000 Mius for E5, and equals to 2000 Mius for electrodes E5, E10 and E15. In the third return, recovery time of E5 increased to 2000 Mius and in E20 decreased to 1000 Mius, in most subjects. The comparison of the different models has shown that the Cochlear Implant N24 R (CS) has presented the highest amplitudes, the highest slopes and the lowest latencies, and the lowest p-NRT values. CONCLUSION: During the first year of CI use, the electrical stimulation released by intracochlear electrodes did not cause significant changes of ECAP characteristics, except in the increase of N1 peak amplitude.

Post-implantation facial nerve stimulation is a common side-effect of cochlear electrical stimulation. Facial nerve stimulation can often be resolved through adjustments in speech processor fitting but, in some instances, exhibit limited benefit or may have a detrimental effect on speech perception. In this study, the apical reference stimulation mode was investigated as a potential intervention to facial nerve stimulation. Firstly, a model refinement software tool was developed to improve the accuracy of models created by an automated workflow. Secondly, the refined model of the human cochlea, facial nerve and electrode array, coupled with a neural model, was used to predict excitations of auditory and facial nerve fibres. Finally, psychoacoustic tests were used to determine auditory comfort and threshold levels for the apical reference stimulation mode while simultaneously capturing electromyography data. The refinement tool illustrated an improved accuracy compared to measured data. Models predicted a desirable outcome for apical reference stimulation, as facial nerve fibre thresholds were higher and auditory thresholds were lower, in direct comparison to conventional monopolar stimulation. Psychoacoustic tests illustrated decreased auditory thresholds and increased dynamic range during apical reference stimulation. Furthermore, apical reference stimulation resulted in lower electromyography energy levels, compared to conventional monopolar stimulation, which suggests a reduction in facial nerve stimulation. Subjective feedback corroborated that apical reference stimulation alleviated facial nerve stimulation. This suggests that apical reference stimulation may be a viable strategy to alleviate facial nerve stimulation considering the improvements in dynamic range and auditory thresholds, complemented with a reduction in facial nerve stimulation / Dissertation (MEng (Bioengineering))--University of Pretoria, 2019. / NRF / Electrical, Electronic and Computer Engineering / MEng (Bioengineering) / Unrestricted

The objective of this study was to describe the influence of tinnitus distress on quality of life (QoL) outcomes in adult cochlear implant (CI) recipients who experience tinnitus, and to investigate the prognostic significance of tinnitus distress over time. A retrospective, longitudinal study of 210 adult (_18 years) CI recipients implanted between 2001 and 2017 was conducted. Data on hearing-related QoL, using the Abbreviated Profile of Hearing Aid Benefit (APHAB) and tinnitus distress, using the Tinnitus Reaction Questionnaire (TRQ) were captured preoperatively as well as at 6-months, 12-months and >24-month postoperatively. The effect of tinnitus distress on hearing-related QoL outcomes over time was determined. Furthermore, 13 potential predictive factors were identified from the retrospective dataset, including demographic, hearing loss, CI, speech perception and tinnitus related factors. Multiple regression analyses were performed to identify variables that influence hearing-related QoL outcomes over time. Lower tinnitus distress and younger age at implantation were the only two out of 13 possible predictor variables that were identified as significant predictors of better hearing-related QoL in adult CI recipients. A general trend of statistically significant (p<0.01) tinnitus relief was evident from the preoperative interval to the 6-months, 12-months and >24-months postoperative intervals, confirming significant relief in tinnitus distress up to more than two years post-implantation. Within this dataset, higher levels of tinnitus distress were associated with poorer hearing-related QoL outcomes, as confirmed by the negative correlation between tinnitus distress and hearing-related QoL. This study contributes to a better understanding of the complex influence that multifactorial variables has upon the hearing-related QoL outcomes of adult CI recipients. This enables clinicians to provide evidence-based preoperative counselling combined with postoperative rehabilitation to adult CI recipients and their families. Not only was tinnitus distress confirmed as a predictive factor for hearing-related QoL in this study, but also the association between residual tinnitus distress and hearing-related QoL. These results emphasize the importance of identification, counselling and timely monitoring of adult CI recipients who experience tinnitus. / Dissertation (MA)--University of Pretoria, 2019. / Speech-Language Pathology and Audiology / MA / Unrestricted

Thesis (MAud (Interdisciplinary Health Sciences. Speech-Language and Hearing Therapy)--Stellenbosch University, 2008. / Individuals are increasingly undergoing bilateral cochlear implantation in an attempt to benefit from binaural hearing. The main aim of the present study was to compare the speech recognition of children fitted with bilateral cochlear implants, under binaural and monaural listening conditions, in quiet and in noise. Ten children, ranging in age from 5 years 7 months to 15 years 4 months, were tested using the Children’s Realistic Index for Speech Perception (CRISP). All the children were implanted with Nucleus multi-channel cochlear implant systems in sequential operations and used the ACE coding strategy bilaterally. The duration of cochlear implant use ranged from 4 years to 8 years 11 months for the first implant and 7 months to 3 years 5 months for the second implant. Each child was tested in eight listening conditions, which included testing in the presence and absence of competing speech. Performance with bilateral cochlear implants was not statistically better than performance with the first cochlear implant, for both quiet and noisy listening conditions. A ceiling effect may have resulted in the lack of a significant finding as the scores obtained during unilateral conditions were already close to maximum. A positive correlation between the length of use of the second cochlear implant and speech recognition performance was established. The results of the present study strongly indicated the need for testing paradigms to be devised which are more sensitive and representative of the complex auditory environments in which cochlear implant users communicate.

In order to provide evidence demonstrating the efficacy of cochlear implantation in the children enrolled in the Pretoria Cochlear Implant Programme (PCIP), an in-depth analysis of the numerous variables involved in determining each individual child’s success with his/her cochlear implant needs to be undertaken. As the PCIP has been operating for over a decade, a standardised database that includes the variables identified by similar cochlear implant programmes world-wide as being related to outcomes of children with cochlear implants and their families, has to be assembled. As the PCIP functions partly as a paediatric cochlear implant programme, an Early Communication Intervention (ECI) approach with the emphasis on the family unit is of critical importance. To address this need, a comprehensive questionnaire was used in a cross sectional study combining qualitative, and predominantly quantitative methods. The aim was to determine the perceptions of parents/caregivers of children with cochlear implants in the PCIP of the children’s outcomes. The questionnaire was further used to gather relevant data pertaining to children and their families’ biographical, medical, environmental, audiological, linguistic and educational histories and current functioning. A total of 45 participants, all mothers of children with cochlear implants, returned questionnaires. Results indicated that several key factors played a role in determining a positive outcome in the children’s audiological, linguistic, social and educational functioning leading to placement in an inclusive educational setting. These included an early age at diagnosis and prompt fitting of hearing aids and subsequent cochlear implantation, the absence of prenatal and perinatal complications including feeding difficulties, a higher level of maternal education, achievement of developmental milestones within normal age norms, the use of an FM system in the primary school phase, access to ECI, the presence of an older sibling to act as a language model, the absence of birth trauma and congenital rubella syndrome as cause of hearing loss, and later (acquired) onset of hearing loss. Children whose cause of hearing loss was non-syndromic and hereditary or unknown, were more likely to have positive outcomes. The clinical implications for the PCIP were synthesised and presented as a developmental systems model, providing guidelines for the entire process from referral to the cochlear implant programme to exiting of the system. The urgency of the need for a universal newborn or infant hearing screening programme as well as reliable systems of early referral to cochlear implant programmes, emerged strongly in the recommendations of the study. / Dissertation (M (Communication Pathology))--University of Pretoria, 2006. / Speech-Language Pathology and Audiology / Unrestricted

The cochlear implant represents a radical intervention in the hearing-impaired child's life, which has a profound influence on the feelings and emotions of the child's family. In this study it is endeavoured to identify and to describe this influence. A literature study was done. Families of implanted children in Scotland and in South Africa filled in questionnaires and interviews were held. This study illuminates the fact that parents suffer stress and have various concerns before as well as after the implant. Different reasons why parents decide to give their child a cochlear implant are described. The researcher came to the conclusion that the implanted child functions in a more balanced way and that parents are very satisfied after the implantation. The effect of the implant is described under the following categories: communication, feelings of parents, effect on the deaf child, normality, effect on parents, effect on siblings. / Education / M.Ed.(Guidance and Counselling)

The effects of auditory efferent activity on peripheral physiology may be examined by presenting broadband noise (BBN) to the contralateral ear during otoacoustic emission (OAE) recordings. The presentation of BBN typically produces a reduction of OAE amplitudes in comparison to a condition without BBN. This is termed contralateral suppression. Limited information exists regarding the effects of contralateral BBN on responses observed at higher levels in the auditory system. The present study employed this paradigm to investigate interactions of attention and laterality on the transient evoked otoacoustic emission (TEOAE), auditory brainstem response (ABR) and cortical auditory evoked potentials (CAEP) P1-N1-P2. TEOAEs were evoked by 60 dB SPL clicks; ABRs and CAEPs were evoked by 60 dB SPL 2.0 kHz tone pips in 15 normally hearing adults. Four conditions were employed for each ear: 1) quiet (no noise); 2) 60 dB SPL contralateral BBN; 3) words (at -3 dB SNR) embedded in 60 dB SPL contralateral BBN while subjects classified words as animal versus food items; 4) words from condition #3 played backwards and embedded in 60 dB SPL contralateral BBN. For TEOAEs: 1) more suppression was evident in the active attention condition than the passive listening conditions and 2) right ear OAE amplitudes for the 8-18 ms time period exhibited more suppression in the presence of BBN for all noise conditions, although this did not meet statistical significance. For the ABR experiment, amplitudes in the noise conditions decreased in all epochs for the right ear, but not for the left. For the CAEP experiment, asymmetries were evident in temporal regions and an effect of contralateral noise was evident. The outcome of this investigation suggests that efferent activation by noise and active attention has diverse modulatory effects on electroacoustic and electrophysiologic responses along the auditory pathway.

The communicative interchanges of a congenitally deaf child who received a cochlear implant at 24 months of age were videotaped in fifteen hourly sessions over a nine month period while she participated in auditory-verbal therapy prior to and following implantation. The present study examined selected early communicative behaviors. Using Tait's (1993) protocol for charting communicative adult-child interaction, gestures, eye-gaze, and sound uttered either by the child or an adult during communicative interchanges were transcribed from the videotapes. Results corresponded with Tait's, revealing growth in the child's communicative interaction across sessions. In less than three months following implantation phonemic measures rose dramatically. Almost all phonemic measure correlations were significant, high, and positive.

Os objetivos deste trabalho foram: avaliar os efeitos das diferentes relações sinal/ruído, no reconhecimento da fala com o implante coclear; comparar o reconhecimento da fala no ruído, com diferentes tipos de implantes cocleares multicanais; avaliar a influência do tempo de surdez, tempo de uso do implante coclear e progressão da surdez, no reconhecimento da fala com o implante coclear e avaliar o grau de dificuldade dos usuários de implante coclear, em situações com ruído competitivo no dia-a-dia. Foram selecionados 40 adultos com deficiência auditiva pós-lingual, com os implantes cocleares Nucleus 22 (N=13, estratégia SPEAK), Nucleus 24 (N=7, estratégia ACE), Combi 40 (N=6), Combi 40+ (N=7) e Clarion (N=7) com a estratégia CIS, com experiência de mais 6 meses de uso do implante coclear e reconhecimento de fala em conjunto aberto. Foi avaliado o reconhecimento das sentenças CPA (Valente 1998), no silêncio e nas relações S/R de +15 dB, +10 dB, +5 dB e aplicado o questionário Social Hearing Handicap Index - SHHI (Wedel e Tegtmeier 1979, Wedel 1983), para a auto-avaliação do desempenho com o implante coclear, em situações de silêncio (componente da deficiência auditiva) e ruído (componente da seletividade), no dia-a-dia. Os usuários de todos os tipos de implante coclear apresentaram redução significativa dos índices de reconhecimento de sentenças CPA, em função da diminuição da relação S/R, com a curva das medianas de reconhecimento das sentenças CPA alcançando 50% na relação S/R de +10 dB. Não houve diferença estatisticamente significante nos índices de reconhecimento das sentenças CPA e escores de dificuldade do Social Hearing Handicap Index (SHHI), obtidos com os diferentes tipos de implantes cocleares e estratégias de codificação da fala. As dificuldades dos usuários de implante coclear foram raras nas situações de silêncio (componente da deficiência auditiva) e ocasionais nas situações com ruído competitivo (componente da seletividade), no questionário SHHI. Observou-se, também, a influência das características dos sujeitos (tempo de surdez, tempo de uso do implante coclear e progressão da surdez) nos índices de reconhecimento das sentenças CPA. O presente estudo permitiu concluir que os usuários de todos o tipos de implante coclear multicanais apresentaram redução dos índices de reconhecimento da fala, em função da diminuição da relação S/R e maior dificuldade, no dia-a-dia, em ambientes com ruído competitivo, do que no silêncio. / The aims of this study were: to evaluate the effects of different signal to noise ratios on speech recognition obtained by the use of the cochlear implant; to compare the speech recognition in noise with different types of multichannel cochlear implants; to evaluate the influence of duration of deafness, time of implant use and hearing loss progression in the speech recognition with cochlear implant and to evaluate the degree of difficulty for speech understanding in noise in daily life situations as well. Forty adults with post lingual hearing loss implanted with Nucleus 22 (n=13, SPEAK strategy), Nucleus 24 (n=7, ACE strategy), Combi 40 (n=6, CIS strategy), Combi 40+ (n=7, CIS strategy) and Clarion (n=7, CIS strategy). The minimum time of implant use was 6 months. All subjects enjoyed some degree of open set recognition. It was evaluated the recognition for CPA sentences (Valente 1998), in silence and in S/N +15, +10 and +5 dB. It was also applied the Social Hearing Handicap Index - SHHI questionnaire (Wedel e Tegtmeier 1979, Wedel 1983) for self assessment in daily life in silence (hearing loss component) and noise (selectivity component). All the implanted adults presented a significant reduction in the scores for sentences recognition as the S/N decreased. The medians´ curve for sentence recognition reached 50% in the signal to noise ratio of +10 dB. There was no difference statistically significant in sentences recognition scores and difficulty scores obtained with the Social Hearing Handicap Index (SHHI), for all types of implants and different speech strategy. The difficulties of implanted adults were rare in silence (hearing loss component) and occasional in noisy situations (selectivity component) in the SHHI questionnaire. It was also observed the influence of duration of deafness, time of implant use and hearing loss progression in the sentences recognition scores. In this study it was concluded that all subjects presented a significant reduction in sentences recognition scores as the S/N decreased and all subjects showed more difficulty for speech understanding in noisy environments independently of the type of multichannel cochlear implants used.