Thesis (B.Sc.)--University of Hong Kong, 2003. / "A dissertation submitted in partial fulfilment of the requirements for the Bachelor of Science (Speech and Hearing Sciences), The University of Hong Kong, April 30, 2003." Includes bibliographical references (p. 29-32) Also available in print.

Thesis (B.Sc)--University of Hong Kong, 2007. / "A dissertation submitted in partial fulfilment of the requirements for the Bachelor of Science (Speech and Hearing Sciences), The University of Hong Kong, June 30, 2007." Includes bibliographical references (p. 26-30). Also available in print.

Thesis (M. Aud.)--University of Canterbury, 2009. / Typescript (photocopy). Includes bibliographical references (p. 92-96). Also available via the World Wide Web.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Degertekin, F. Levent; Committee Member: Baldwin, Daniel; Committee Member: Hesketh, Peter. Part of the SMARTech Electronic Thesis and Dissertation Collection.

No description available.

Thesis (M.S.)--University of Texas at Dallas, 2008. / Includes vita. Includes bibliographical references (leaves 75-78)

The reduced speech intelligibility caused by feed feedback oscillation is a major problem for hearing aid users. The demand for improved signal quality has led researchers to look for feedback reduction techniques. In this Thesis, we studied several feedback reduction schemes with emphasis in adaptive feedback cancellation algorithms. The main goal was to develop a system for feedback cancellation that is able to adapt to non-stationary environments while having reasonable computational complexity. This requirement is imposed by the need to implement the feedback cancellation scheme in low power DSP systems. In Chapter 1, we briefly introduced hearing aid systems. We examined the parts that are made of and the types of hearing aids that are available in the market. Then, we described the mechanism that causes feedback oscillation in hearing aids and the adverse effects it has on signal quality. Chapter 2 contains some theoretical results on the field of adaptive linear system identification algorithms and simulation results that support this theory. The chapter begins by giving a derivation of the popular LMS algorithm. A theoretical analysis of LMS using the independence assumption is also provided. Then we are concerned with the least squares filter. We described the RLS algorithm and a linear complexity version of it, the FAEST algorithm. Subsequently, we discussed the FNTF algorithm that trades computational complexity for performance in solving the system identification problem. Next, we developed a new algorithm, the FLMS, by making simplifications to FNTF. We also proved that the proposed algorithm outperforms LMS at least when the input signal is an AR process. Finally, we provided simulation results which prove the superiority of FLMS over LMS. Chapter 3 is devoted in using some algorithms described in Chapter 2 for feedback cancellation in hearing aids. The chapter begins with a hearing aid model that includes an acoustic feedback mechanism. On this system, a linear filter is added that estimates the acoustic feedback so that it can be removed from he signal captured by the microphone. The feedback estimation is performed with LMS and FLMS. Using simulation results, we saw that FLMS can be successfully used in feedback systems and continues to outperform LMS. We also saw that, contrary to the open loop case, when feedback is present, the stochastic approximation theory does not satisfactorily predict the mean learning curves of LMS. / Ένα από τα σημαντικότερα προβλήματα που πρέπει να αντιμετωπιστούν κατά το σχεδιασμό ενός ακουστικού βαρηκοΐας είναι αυτό της ακουστικής ανάδρασης. Με τον όρο ακουστική ανάδραση αναφερόμαστε στο φαινόμενο κατά το οποίο ένα μέρος της εξόδου του ακουστικού επιστρέφει στην είσοδο και ενισχύεται εκ νέου. Γνωστό και ως μικροφωνισμός, το φαινόμενο αυτό γίνεται αντιληπτό από τους ασθενείς ως ένα συνεχές σφύριγμα και είναι ιδιαίτερα ενοχλητικό. Για την αντιμετώπιση του φαινομένου έχουν προταθεί διάφορες τεχνικές. Για παράδειγμα, ο περιορισμός του κέρδους ενίσχυσης στις συχνότητες όπου εμφανίζεται ο μικροφωνισμός είναι μια λύση που συναντάται συχνά σε αναλογικά ακουστικά βαρηκοΐας. Η μέθοδος αυτή, όμως, απαιτεί τον προσδιορισμό των επικίνδυνων συχνοτήτων κατά τη διαδικασία προσαρμογής του ακουστικού στον εκάστοτε ασθενή. Ακόμα και αν ο προσδιορισμός γίνει με μεγάλη ακρίβεια, οι συχνότητες στις οποίες εμφανίζεται ο μικροφωνισμός αλλάζουν κατά τη διάρκεια χρήσης του ακουστικού, περιορίζοντας έτσι την αποτελεσματικότητα της μεθόδου. Με την καθιέρωση της ψηφιακής τεχνολογίας στα ακουστικά βαρηκοΐας, εμφανίζονται νέες δυνατότητες για την αντιμετώπιση του μικροφωνισμού. Είμαστε σε θέση, πλέον, να μοντελοποιήσουμε το σύστημα της ακουστικής ανάδρασης και να χρησιμοποιήσουμε το μοντέλο αυτό για εξαλείψουμε το μικροφωνισμό. Για την μοντελοποίηση αυτή χρησιμοποιείται κατά κόρον ο αλγόριθμος LMS. Η χαμηλή υπολογιστική πολυπλοκότητα που τον χαρακτηρίζει τον κάνει ιδανικό για ακουστικά βαρηκοΐας. Στην εργασία αυτή παρουσιάζουμε έναν νέο αλγόριθμο, επίσης χαμηλής πολυπλοκότητας, για το πρόβλημα της αναγνώρισης γραμμικών συστημάτων. Αποδεικνύουμε με μαθηματικό τρόπο ότι είναι πιο αποτελεσματικός από τον LMS για συγκεκριμένα μοντέλα σημάτων εισόδου, ενώ με εξομοιώσεις ότι υπερτερεί του LMS και για πολύ πιο γενικές εισόδους. Επιπρόσθετα, δείχνουμε ότι ο νέος αλγόριθμος μπορεί να χρησιμοποιηθεί για την ακύρωση της ανάδρασης σε ακουστικά βαρηκοΐας, όπου παραμένει πιο αποτελεσματικός από τον LMS.

Introdução: A Telessaúde caracteriza-se pelo uso da tecnologia de informação e comunicação na área da saúde. Na Fonoaudiologia, o uso desta ferramenta por meio da Teleducação e Teleassistência se caracteriza como uma importante estratégia que leva a informação para alunos, profissionais, pacientes e comunidade em geral. Esse fator, aliado à grande extensão geográfica do Brasil e a distribuição heterogênea dos profissionais da saúde, vem ao encontro da necessidade de atendimento especializado para pacientes e descentralização do conhecimento para profissionais. Neste contexto, o uso da Teleducação emerge como uma proposta para minimizar as dificuldades encontradas pelo paciente, no processo de adaptação do aparelho de amplificação sonora individual (AASI), na qual muitos materiais educacionais são produzidos com o intuito de orientar e facilitar a adaptação do indivíduo deficiente auditivo, à sua nova realidade. Objetivo: Este projeto tem por objetivo elaborar um programa de capacitação por meio da Teleducação Interativa, sobre o aparelho de amplificação sonora individual, e analisar a eficácia do mesmo, quanto ao aprendizado e motivação dos profissionais. Resultados: A primeira etapa compreendeu a elaboração do programa de capacitação, na qual foi desenvolvido um cybertutor sobre o tema AASI e as ferramentas fórum de discussão e web conferência, com o intuito de complementar o aprendizado. Na segunda etapa, referente à análise do programa, verificou-se que não houve significância estatística no aspecto relacionado ao aprendizado do conteúdo, na avaliação pré e pós teste. Em relação à motivação dos profissionais, o estudo obteve resultado positivo, sendo avaliado como curso impressionante. Discussão: O programa de capacitação foi desenvolvido, respaldado em estudos voltados para elaboração de materiais didáticos à distância. No que se referem aos resultados da avaliação, todas as dificuldades encontradas neste aspecto corroboraram com a literatura. Conclusão: A elaboração do Programa de Capacitação por meio da Teleducação Interativa sobre o tema aparelho de amplificação sonora individual (AASI) foi realizada satisfatoriamente, alcançando um índice de motivação em relação à participação altamente positivo, porém os resultados da comparação da avaliação da situação problema pré e pós teste não foram estatisticamente significantes. / Introduction: Telehealth is characterized by the use of information technology and communication in healthcare. In audiology, the use of this tool through Telecare and Tele-education is characterized as an important strategy that leads the information for students, professionals, patients and the general community. This factor, combined with the large geographical extent of Brazil and the heterogeneous distribution of health professionals, meets the need of specialized care for patients and decentralization of knowledge for professionals. In this context, the use of Tele-education has emerged as a proposal to minimize the difficulties encountered by the patient in the process of adaptation of a hearing aids (HA), in which many educational materials are produced in order to guide and facilitate the adaptation HA to their new reality. Objective: This project aims to develop a training program through the Interactive Tele-education on the individual sound amplification devices, and analyze the effectiveness of the same as learning and motivation. Results: The first stage of the preparation of the training program, which was developed on the theme Cybertutor hearing aids and tools discussion forum and web conferencing in order to supplement learning. In the second stage, regarding the analysis of the program, it was found that there was no statistical significance in the learning aspect of the content, in the pre and post test. Regarding the motivation of staff, the study was positive, which was assessed as \"impressive progress\". Discussion: The training program was developed, backed up by studies aimed at developing distance learning materials. In that refer to results of the evaluation, all difficulties found in this aspect corroborated with the literature. Conclusion: The development of the Training Program through the Interactive Tele-education on the subject of HA was performed satisfactorily, reaching a level of motivation in relation to participation highly positive, but the comparison results of the evaluation of the problem situation pre and post-test were not statistically significant.

Introdução: O uso de métodos prescritivos na programação do aparelho de amplificação sonora individual (AASI) tem como principal objetivo a aplicação da amplificação recomendada aos usuários, melhorando a audibilidade de sons suaves e fala conversacional e garantindo conforto para sons fortes. Diferentes métodos, no entanto, podem ter diferentes objetivos de ajuste. Considerando as modificações nas estruturas do meato acústico externo do indivíduo idoso, se faz necessário um direcionamento do processo de seleção e adaptação do AASI nessa população, propondo um protocolo individualizado e que leve em conta os ajustes recomendados pelos métodos de prescrição. Objetivo: Analisar comparativamente os métodos prescritivos NAL-NL2 e DSL v5.0a de acordo com programação individualizada do AASI para o indivíduo idoso com deficiência auditiva. Metodologia: Participaram do estudo 60 indivíduos idosos com deficiência auditiva. Após a assinatura do Termo de Consentimento Livre e Esclarecido, os participantes do estudo foram submetidos à realização da meatoscopia, mensuração da RECD (Real Ear to Coupler Difference) e programação individualizada do AASI com os métodos prescritivos NAL-NL2 e DSL v5.0a. A verificação do desempenho com cada prescrição foi realizada por meio das medidas da REAR (Real Ear Aided Response), cálculo do SII (Speech Intelligibility Index) e teste HINT (Hearing In Noise Test). A análise estatística comparativa dos dados obtidos nas duas situações foi realizada por meio dos testes t pareado e de Wilcoxon. Resultados: Houve diferença estatisticamente significante com melhor desempenho do método NAL-NL2 na avaliação da REAR nas faixas de frequências baixas e altas para sons de entrada de média e forte intensidade, na faixa de frequência alta para sons de entrada de fraca intensidade, e no cálculo do índice de inteligibilidade de fala para sons de entrada fracos. O método DSL v5.0a apresentou melhores resultados com diferença estatisticamente significante na avaliação da REAR em frequências médias para sons de entrada médios, em frequências baixas e médias para sons de entrada fracos, no cálculo do índice de inteligibilidade de fala para sons de entrada médios e fortes, e no teste HINT nas situações de silêncio e ruído. Conclusões: Não foi possível estabelecer um método mais adequado em todos os parâmetros avaliados. Na avaliação da percepção de fala houve uma diferença importante com melhor resultado para o método DSL v5.0a, o que oferece uma alternativa satisfatória em relação à percepção de fala no silêncio e no ruído e viabiliza a utilização deste método com a população idosa. A continuidade de estudos envolvendo o indivíduo idoso é de extrema relevância, considerando as características individuais desta população e a necessidade de estabelecer uma prática clínica específica para a mesma. O estabelecimento de diferentes perfis audiológicos dentre esta população é importante para determinar qual a melhor conduta para cada um no contexto da programação e adaptação do AASI, conforme todas as etapas e parâmetros a serem levados em consideração para um melhor resultado. / Introduction: The use of prescriptive methods in the hearing aids programming has as main objective the application of the recommended amplification to the users, improving the audibility of soft sounds and conversational speech and guaranteeing comfort for loud sounds. Different methods, however, may have different adjustment goals. Considering the modifications in the structures of the external acoustic meatus of the elderly patient, an orientation of the hearing aids selection and adaptation process in this population is necessary, proposing an individualized protocol that take into account the adjustments recommended by the prescription methods. Objective: To comparatively analyze the NAL-NL2 and DSL v5.0a prescriptive methods according to the hearing aids individualized programming for the elderly with hearing impairment. Methodology: The study included 60 elderly individuals with hearing impairment. After signing the Free Informed Consent Form, the participants of the study underwent a meatoscopy, RECD (Real Ear to Coupler Difference) measurement and hearing aids individualized programming with the prescriptive methods NAL-NL2 and DSL v5.0a. Performance verification for each prescription was performed using REAR measurements (Real Ear Aided Response), SII calculation (Speech Intelligibility Index) and HINT (Hearing In Noise Test). Comparative statistical analysis of the data obtained in both situations was performed using the paired t test and the Wilcoxon test. Results: There were statistically significant differences with a better performance of the NAL-NL2 method in the REAR evaluation in low and high frequency bands for medium and loud intensity input sounds, in the high frequency range for low intensity input sounds, and in the speech intelligibility index calculation for soft input sounds. DSL v5.0a presented better results with statistically significant difference in the REAR evaluation in medium frequencies for medium input sounds, in low and medium frequencies for soft input sounds, in the speech intelligibility index calculation for medium and loud input sound, and in the HINT test in silence and noise situations. Conclusions: It was not possible to determine a most suitable method for all evaluated parameters. On the speech perception evaluation there was an important difference having the DSL v5.0a method achieved better results, which offers a satisfactory alternative regarding speech perception in silence and noise conditions and allows the use of this method with the elderly population. The continuity of studies involving the elderly is extremely relevant considering the individual characteristics of this population and the need to establish a specific clinical practice for them. The establishment of different audiological profiles among this population is important to determine the best conduct for each one in the context of hearing aids programming and adaptation, according to all the steps and parameters to be taken into account for a better result.

In binaural hearing aids, several beamforming algorithms can be used. These beamformers aim to enhance the target speech signal and preserve the binaural cues of the target source (e.g. with constraints on the target). However, the binaural cues of the other directional sources as well the background noise are often lost after processing. This affects the global impression of the acoustic scene, and it limits the perceptual separation of the sources by the hearing aids users. To help the hearing aids users to localize all the sound sources, it is important to keep the binaural cues of all directional sources and the background noise. Therefore, this work is devoted to find the best trade-off between the noise/interferers reduction and the cues preservations not only for the directional interferers but also for the background noise based on selection and mixing processes. In this thesis, some classification decision algorithms, which are based on different criteria such as the power, the power difference, and the coherence, are proposed to complete the selection and mixing processes. Simulations are completed using recorded signals provided by a hearing aid manufacturer to validate the performance of the proposed algorithm under different realistic acoustic scenarios. After detailed testing using different complex acoustic scenarios and different beamforming configurations, the results indicate that some of the proposed classification decision algorithms show good promise, in particular the classification decision algorithm based on coherence.