Made available in DSpace on 2015-07-22T20:50:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-01-26. Added 1 bitstream(s) on 2015-08-11T03:26:03Z : No. of bitstreams: 1 Publico-12529a.pdf: 1382817 bytes, checksum: 65bd98549521fbf2650836a170f9761e (MD5). Added 1 bitstream(s) on 2015-08-11T03:26:03Z : No. of bitstreams: 2 Publico-12529a.pdf: 1382817 bytes, checksum: 65bd98549521fbf2650836a170f9761e (MD5) Publico-12529b.pdf: 1113563 bytes, checksum: 3261d75b2356f849d087c69443322b57 (MD5) / As BMPs, proteínas indutoras de crescimento ósseo, desde o início de sua utilização têm sido avaliadas em diferentes modelos experimentais objetivando determinar sua eficácia. Sabemos que algumas substâncias podem interferir positiva ou negativamente quando utilizadas de forma sistêmica ou local, associadas à BMP. Objetivo: Este estudo tem por objetivo avaliar as possíveis interferências da utilização de antibioticoterapia profilática pré e pós-operatória, utilizando-se como princípio ativo a cefazolina, aplicada a um modelo experimental em coelhos. Métodos: Foram utilizados dois grupos de coelhos fêmea, neozelandeses, submetidos à artrodese intertransversa da coluna lombar, segmento L5-L6, por via posterior. No primeiro grupo foi utilizado o enxerto autólogo associado ao biocomposto (BMP bovino, 1,0mg e hidroxiapatita, 9,0mg). No segundo grupo foi realizado o mesmo procedimento e utilizado o mesmo biocomposto, porém os animais foram submetidos a antibioticoterapia profilática com cefazolina iniciada duas horas antes e mantida por 24 horas após o término do procedimento. Os animais foram acompanhados por 15 semanas, isolados em cativeiro e avaliados diariamente por veterinário sob o ponto de vista clínico e neurológico, sendo posteriormente sacrificados e retiradas as peças cirúrgicas para serem submetidas à análise radiográfica e histológica. Resultados: Para o grupo 1, a quantidade e localização do material implantado variaram entre os indivíduos, porém, na maioria dos casos (6 amostras), a quantidade de partículas de osso homólogo era insignificante e estava dispersa ao longo do tecido mole que recobre o dorso da vértebra, circundado por tecido reacional com área de necrose. Nos demais casos as partículas com reabsorção preenchiam o reduzido espaço entre os processos transversos. Para o grupo 2, a quantidade do material e sua localização também variaram entre os indivíduos. Na maioria dos casos inúmeras partículas de osso mole preenchiam o espaço entre os processos laterais cuja neoformação óssea levou ao aprisionamento de algumas dessas partículas. Todos os casos exibiram formação em maior ou menor intensidade de tecido cartilaginoso na superfície dos processos transversos. A análise radiográfica mostrou em sua freqüência relativa maior freqüência de fusão completa para o grupo 2 quando comparado ao grupo 1. Conclusão: Do ponto de vista histológico para o modelo e período experimental analisado, inferimos que, embora nenhum dos tratamentos propostos tenha promovido o completo fusionamento das vértebras por tecido ósseo, a utilização de osso homólogo + BMP bovina, associada à aplicação de cefazolina, promoveu maior formação cartilaginosa e óssea com menor índice de rejeição do material enxertado na área doadora, quando comparada ao grupo sem associação de cefazolina. Do ponto de vista radiográfico, a análise relativa também demonstrou-se superior para o grupo onde foi utilizado cefazolina. / The BMPs, the inductive proteins of bone growth since the beginning of their use have been evaluated in different experimental models aiming to determine their efficacy. We know that some substances can interfere positively or negatively when used in a systemic way or places associated with the BMP. Objective: this study objective to evaluate the possible interferences of antibiotic-therapy by using the active principle of cefazolin in an experimental model with rabbits. Methods: Two groups of female New Zealand rabbits underwent a lumbar spine inter-transverse artrodesys of segment L5-L6 using posterior approach. An homolog bone graft associated with a bio-compound (bovine BMP, 1,0mg and hydroxiapatita, 9,0mg) was used in the first group. The same procedure and bio-compound were used in the second group. However the animals were submitted to a prophylactic antibiotic-therapy with cefazolin starting two hours before the procedure and maintained for 24 hours after surgery. The animals were analyzed for 15 weeks, isolated in captivity and daily evaluated by a veterinarian under the clinical and neurological views and then euthanized, being the surgical pieces removed and submitted to a radiological and histological analysis. Results: For the first group the quantity and location of the implanted material varied among the individuals. However in most of the cases, the quantity and particles of homolog bone was insignificant and disperse along the soft tissue that covers the posterior region of the vertebrae. In the other cases, the particles with reabsorvation filled the reduced space between the transversal processes. For the second group, the quantity of material and its location also varied among the individuals. In most of the cases, several particles of homolog bone filled the space between the lateral processes whose bone neo-formation led to a trapping of these particles. All the cases showed formation in a higher or lower intensity of the cartilaginous tissue in the surface of the transverse processes. The radiological analysis showed in its relative frequency a higher frequency of complete fusion for group 2 when compared to group 1. Conclusion: Under the histological view for the model and experimental period analyzed, we inferred that, despite the fact that none of the proposed treatments had promoted a complete fusion of the vertebraes per bone tissue, the use of homolog bone + bovine BMPs associated with the use of cefazolin promoted a higher cartilaginous and bone formation with lower incidence of rejection of the material grafted in the doer area when compared to the group without the association of cefazolin. Under the radiological view, the relative analysis also showed to be superior in the group where cefazolin was used as a prophylactic antibiotic. / TEDE / BV UNIFESP: Teses e dissertações

Conventional hearing aid circuitry is often unable to provide children with hearing loss with sufficient high frequency information in order to develop adequate oral language skills due to the risk of acoustic feedback and the narrower frequency spectrum of conventional amplification. The purpose of this study was to investigate word recognition abilities of children with moderate-to-severe hearing loss using hearing aids with linear frequency transposition. Seven children with moderate-to-severe sensorineural hearing loss between the ages of 5 years 0 months and 7 years 11 months were selected for the participant group. Word recognition assessments were first performed with the participants using their own previous generation digital signal processing hearing aids. Twenty-five-word lists from the Word Intelligibility by Picture Identification (WIPI) test were presented to the participants in three test conditions, namely: at 55 dB HL in quiet, 55 dB HL with a +5 dB signal-to-noise ratio (SNR) and at 35 dB HL. The participants were then fitted with an ISP-based hearing aid without linear frequency transposition, and the word recognition assessments were repeated with different WIPI word lists under the same conditions as the first assessment. Linear frequency transposition was then activated in the ISP-based hearing aid and different WIPI word lists were presented once more under identical conditions as the previous assessments. A 12-day acclimatization period was allowed between assessments, and all fittings were verified according to the DSL v5 fitting algorithm. Results indicated a significant increase of more than 12% in word recognition score for some of the participants when they used the ISP-based hearing aid with linear frequency transposition. A significant decrease was also seen for some of the participants when they used the ISP-based hearing aid with linear frequency transposition, but all participants presented with better word recognition scores when they used the ISP-based hearing aids without linear frequency transposition compared to their previous generation digital signal processing hearing aids. This study has shown that linear frequency transposition may improve the word recognition skills of some children with moderate-to-severe sensorineural hearing loss, and more research is needed to explore the criteria that can be used to determine candidacy for linear frequency transposition. / Dissertation (MCommunication Pathology)--University of Pretoria, 2010. / Speech-Language Pathology and Audiology / Unrestricted

There has always been a need for objective tests that assess auditory function in infants, young children, and/or any patient whose development level precludes the use of behavioral audiometric techniques. Although the Auditory Brainstem Response (ABR) is seen as the ‘gold standard’ in the field of objective audiometry, it presents with its own set of limitations. The Auditory Steady State Response (ASSR) has gained considerable attention and is seen as a promising addition to the AEP ‘family’ to address some of the limitations of the ABR. The ASSR promises to estimate all categories of hearing loss (mild to profound) in a frequency specific manner. It also indicates to the possibility to validate hearing aid fittings by determining functional gain of hearing aids by determining unaided and aided ASSR thresholds. An exploratory research design was selected in order to compare unaided thresholds, obtained through the use of three different procedures – ABR, ASSR and behavioral thresholds. Aided thresholds were also obtained and compared with two procedures – the aided ASSR (measured and predicted) and aided behavioral threshold. The results indicated that both the ABR (tone burst and click) and ASSR provided a reasonable estimation of the subsequently obtained behavioral audiograms. The ASSR, however, approximated the behavioral thresholds closer than the ABR and were furthermore able to quantify hearing thresholds accurately for subjects with severe and profound hearing losses. The result indicated further that the ASSR can be instrumental in the validation process of hearing aid fittings in infants. These results demonstrated however, that the ASSR measured thresholds underestimate the aided behavioral thresholds and the aided ASSR predicted thresholds overestimate the aided behavioral thresholds. The research concluded that the ASSR is useful in estimating frequency-specific behavioral thresholds accurately in infants and validating hearing aid fittings. Until evidence is sufficient to recommend the ASSR as primary electrophysiological measure of hearing in infants, the ASSR should be used in conjunction with the ABR – following a test battery approach in the diagnostic process of hearing loss in infants. The ASSR further shows great promise in validating hearing aid fittings, but this specific application of the ASSR needs further research evidence on large groups to validate the procedure. / Dissertation (Master of Communication Pathology)--University of Pretoria, 2007. / Speech-Language Pathology and Audiology / unrestricted

Les aides auditives (AA) sont les principaux outils d’intervention de réadaptation recommandés aux personnes âgées ayant une perte auditive, car elles offrent un large éventail d’avantages. Cependant, beaucoup de personnes qui possèdent des AA ne les utilisent pas ou les sous-utilisent. La raison la plus récurrente exprimée par ces non-utilisateurs d’AA est la difficulté persistante à comprendre les conversations dans des environnements bruyants. Il n’est pas mentionné si ces personnes ont essayé de porter leurs AA pendant un certain temps avant de décider de ne plus les porter. Dans l’éventualité où elles auraient abandonné peu de temps après l’obtention de leurs AA, il est possible que ces individus n’aient pas bénéficié d’une adaptation optimale à l’environnement sonore, appelée acclimatation auditive. L’objectif principal de cette thèse est d’évaluer l’apport de l’expérience avec les AA sur l’acclimatation auditive. La première étude visait à déterminer, au moyen d'une revue systématique, si un effet d’acclimatation se produit après l’utilisation d’AA et, le cas échéant, à établir l’amplitude et l’évolution dans le temps de cet effet. Quatorze articles évaluant l’acclimatation via des mesures comportementales, d’auto-évaluation et électrophysiologiques répondaient aux critères d’inclusion et d’exclusion. Bien que leur qualité scientifique générale soit faible ou très faible, les résultats de la revue systématique appuient l’hypothèse qu’un effet d'acclimatation est présent, tel que documenté par les trois types de mesures. Pour la reconnaissance de la parole dans le bruit, l’amélioration varie entre 2 et 3 dB en termes de rapport signal sur bruit (RSB) sur une période minimale d'un mois. Cette étude met en évidence l'importance d’utiliser les AA après l’appareillage afin d’optimiser les bénéfices que celles-ci peuvent procurer. L’objectif du deuxième article était de rapporter les résultats d’une étude longitudinale pour déterminer si l’acclimatation aux AA des personnes âgées peut être évaluée par leurs performances à des tâches de reconnaissance de la parole dans le bruit ainsi que par des mesures d’effort auditif. Trente-deux nouveaux utilisateurs d’AA et 15 utilisateurs expérimentés ont été évalués sur une période de 38 semaines en utilisant un paradigme de double tâche. Pour les nouveaux utilisateurs, les résultats ont révélé une amélioration significative de 2 dB RSB sur un test de reconnaissance de la parole dans le bruit après quatre semaines d’utilisation des AA, et aucune diminution de l’effort auditif, tel que mesuré par le coût proportionnel de la double tâche et par le temps de réponse à la tâche secondaire. Chez les utilisateurs expérimentés, les résultats n’ont dévoilé aucune amélioration de leur performance de reconnaissance de la parole dans le bruit suite à l’utilisation des AA. En conclusion, les résultats confirment la présence d’un effet d’acclimatation tel qu’évalué par des mesures comportementales, d’auto-évaluation et électrophysiologiques suite à une utilisation régulière d’AA. Plus précisément, les nouveaux utilisateurs présentaient une amélioration cliniquement significative de 2 à 3 dB en termes de RSB après une utilisation régulière de leurs AA. Par conséquent, les nouveaux utilisateurs d’AA devraient être informés de cette possible amélioration au fil du temps, car cela pourrait les inciter à continuer de s’adapter à leurs AA plus longtemps avant de décider de les utiliser ou non. / Hearing aids (HAs) are the primary rehabilitation intervention recommended for older adults with hearing loss, as they provide a wide range of benefits. However, a large proportion of individuals who own HAs does not use or underuse them. The most recurring reason reported by non-HA users is their difficulty to understand conversations in noisy environments even when they use HAs. It is unclear if these individuals tried to use their HAs for an extended period of time before abandoning their use. If they gave up too soon after being fitted with their HAs they may not have benefited from an auditory adaptation to the new auditory stimulation, referred to as auditory acclimatization. The main objective of this thesis is to evaluate the contribution of HA experience on auditory acclimatization. The first study aimed to determine, by means of a systematic review, if an acclimatization effect occurs after HA use and if so, to establish the magnitude and time-course of this effect. Fourteen articles that assessed acclimatization through behavioural, self-reported and physiological outcomes met the inclusion and the exclusion criteria. Although their general scientific quality was low or very low, the results of systematic review support the existence of an acclimatization effect as calculated by all three types of outcome measures. For speechrecognition- in-noise performance, improvement ranged from 2 to 3 dB in signal-to-noise ratio (SNR) over a minimum period of 1-month. This study highlights the importance of using the HAs on a regular basis after being fitted with HAs. The goal of the second study was to conduct a longitudinal investigation in order to determine whether acclimatization to HAs by older adults can be assessed data obtained on a speech-recognition-in-noise task and by measures of listening effort. Thirty-two new HA users and 15 experienced HA users were tested over a 38-week period using a dual-task paradigm. For new HA users, the results showed a significant improvement of 2 dB SNR on a speech-recognitionin- noise task after 4 weeks of using the HAs post fitting. Based on the proportional dual-task cost data and by the response time measures recorded on the secondary task. No improvement of speech perception performance in noise was observed for the experienced HA users. 8 The general findings from this thesis support the presence of an acclimatization effect as measured by behavioural, self-reported and physiological measures following regular HA use. Specifically, new HA users show a clinically significant change of 2 and 3 dB SNR on speechrecognition- in noise tasks following their initial fitting. Therefore, new HA users should be informed of the possible improvement in speech recognition over time, as it could entice them to pursue the use of their HAs for a longer period of time before deciding to abandon them.

Alterações temporárias ou permanentes na audição podem ser encontradas nas orelhas submetidas a níveis elevados de pressão sonora. As mudanças temporárias induzidas nas orelhas protetizadas, quando estimuladas por suas próteses auditivas ajustadas na amplificação prescrita, foram avaliadas em um grupo de 25 pacientes após um período controlado (2 a 2 ½ h) de exposição ao ruído presente em um ambiente acústico comum. O estudo foi dividido em três etapas. Uma medida inicial foi realizada na primeira etapa para mensurar a magnitude das mudanças temporárias dos limiares auditivos, induzidas nas 42 orelhas (25 pacientes) durante um período contínuo de exposição ao ruído, com suas próteses auditivas ajustadas na amplificação prescrita. Na segunda etapa, essas 42 orelhas foram divididas em dois grupos distintos: as 22 orelhas protetizadas (13 pacientes) que apresentaram maior mudança temporária inicial nos limiares auditivos foram incluídas no Grupo Experimental e as 20 orelhas protetizadas (12 pacientes) que apresentaram menor mudança temporária inicial nos limiares auditivos foram incluídas no Grupo Convencional. Nesta etapa, as próteses auditivas, adaptadas nas 22 orelhas incluídas no Grupo Experimental, tiveram a sua amplificação reduzida por um período de 60 a 90 dias proposto para o \"treinamento\" das orelhas no uso cotidiano de suas próteses auditivas. Após este período de treino, a amplificação das próteses auditivas retornou ao nível prescrito. No Grupo Convencional, a amplificação prescrita das próteses auditivas adaptadas não foi alterada. Durante esta etapa, quatro medidas das mudanças temporárias induzidas nos limiares auditivos foram realizadas para os dois grupos nas mesmas condições de exposição ao ruído adotadas para a determinação da medida inicial. Uma última medida das mudanças temporárias induzidas nos limiares auditivos foi realizada na terceira etapa, também em idênticas condições. Esta última medida ocorreu em média 30/35 dias depois do término do treinamento, quando os pacientes do Grupo Experimental já faziam o uso cotidiano de suas próteses auditivas reajustadas na amplificação prescrita. A análise estatística de variância (ANOVA) comparou o comportamento das mudanças temporárias induzidas nos limiares auditivos nas três etapas do estudo. Para as orelhas incluídas no Grupo Experimental, foram verificadas alterações estatisticamente significantes (f<0,05) durante as etapas do estudo. As mudanças temporárias induzidas nos limiares auditivos das orelhas incluídas no Grupo Experimental aumentaram nos primeiros quinze a trinta e cinco dias após o inicio do treinamento. Com a continuidade do treinamento essas alterações foram gradualmente se reduzindo. As mudanças temporárias induzidas no final do treinamento (etapa pós-experimental) foram as menores observadas durante o estudo. A redução teve inicio nas freqüências abaixo de 1000 Hz e se extendeu na faixa de freqüência mais afetada nas orelhas protetizadas durante a exposição inicial ao ruído ambiente (250 a 2000 Hz). Para as orelhas incluídas no Grupo Convencional não foram constatadas alterações estatisticamente significantes (f>0,05) nas mudanças temporárias induzidas nos limiares auditivos quando avaliadas nas mesmas condições de exposição ao ruído ambiente. Entretanto, para as freqüências mais graves (250 Hz), foi verificada uma tendência a redução nestas alterações no decorrer do estudo / It is well known that the temporary threshold shift in hearing sensitivity is the most obvious hearing effect of the high level acoustic stimulation. Temporary threshold shifts induced in the aided ears were measured in 25 patients after the use of the hearing aids fitted in the prescribed gain during a controlled exposition time (2 a 2 ½ h) to an environmental noise. The study was performed in three phases. In the first phase a first measure of the temporary threshold shift was obtained for 42 aided ears (25 patients) in order to measure the initial amount of temporary threshold shift induced by the hearing aids fitted in the prescribed acoustic gain. In the second phase the ears were included into two study groups: The Experimental Group (EG) formed by 22 ears (13 patients) with greater temporary threshold shift in the initial measure and the Conventional Group(CG) , formed by 20 ears with the shorter temporary threshold shift in the initial measure . The hearing aids amplification in the 22 aided ears of the Experimental Group was reduced during the daily use for a \"training\" period of about 60 to 90 days, and after that was turned to the prescribed gain. The prescribed gain was not modified to the 20 ears of the Conventional Group. Four measure of temporary threshold shift were performed in the second phase when the patients included in the two groups were exposed to an environmental noise in the same conditions used to obtain the initial measure. The last measure (post-experimental phase) of the temporary threshold shift was performed in the same conditions , 30 days in average after the patients of Experimental Group had returned to use their hearing aids in the prescribed gain. In the Experimental Group, the analysis of the variance (ANOVA) showed significant differences(f<0,05) in the amount of induced temporary threshold shifts measured during the three phases of the study. Fifteen or thirteen five days after the training had begun the amount of temporary threshold shift increase, but with the continuous training it was gradually to reduced .In the end of the study, the last measure (post-experimental phase) was performed and the amount of temporary thresholds shift was very shorter. This reduction of temporary threshold shift was initially verified in the frequencies below 1000 Hz and at the end of the study all of the frequencies initially affected during the exposition time to the environmental noise (250 to 2000 Hz) were significantly reduced. In the ears included in the Conventional Group it was not verified temporary threshold shift statistically significant (f>0,05) in any moment, but in the low frequencies (250 Hz) it was noticed a gradually reduction of the amount of temporary threshold shift during the period of this study

This is an historical investigation into the provision of education services for deaf children in the State of New South Wales in Australia since 1860. The main focus is those deaf children without additional disabilities who have been placed in mainstream classes, special classes for the deaf and special schools for the deaf. The study places this group at centre stage in order to better understand their educational situation in the late 1990s. The thesis has taken a chronological and thematic approach. The chapters are defined by significant events that impacted on the education of the deaf, such as the establishment of special schools in New South Wales, the rise of the oral movement, and aftermath of the rubella epidemic in Australia during the 1940s. Within each chapter, there is a core of key elements around which the analysis is based. These key elements tend to be based on institutions, players, and specific educational features, such as the mode of instruction or the curriculum. The study found general agreement that language acquisition was a fundamental prerequisite to academic achievement. Yet the available evidence suggests that educational programs for most deaf children in New South Wales have seldom focused on ensuring adequate language acquisition in conjunction with the introduction of academic subjects. As a result, language and literacy competencies of deaf students in general have frequently been acknowledged as being below those of five their hearing counterparts, to the point of presenting a barrier to successful post-secondary study. It is proposed that the reasons for the academic failings of the deaf are inherent in five themes. / PhD Doctorate

The objective of this research is to develop and design front-end analog circuits for Capacitive Micromachined Ultrasound Transducers (CMUTs) and optical grating MEMS microphone. This work is motivated by the fact that with micro-scaling, MEMS sense capacitance gets smaller in a CMUT array element for intravascular ultrasound imaging, which has dimensions of 70um x 70um and sub pico-farad capacitance. Smaller sensors lead to a lower active-to-parasitic ratio and thus, degrads sensitivity. Area and power requirements are also very stringent, such as the case of intravascular catheter implementations with CMOS-First CMUT fabrication approach. In this implementation, capacitive feedback charge amplifier is an alternative approach to resistive feedback amplifiers. Capacitive feedback charge amplifier provides high sensitivity, small area, low distortion and saving power. This approach of charge amplifiers is also suitable in capacitive microphones where it provides low power and high sensitivity. Another approach to overcome capacitive detection challenges is to implement optical detection. In the case of biomimetic microphone structure, optical detection overcomes capacitive detection's thermal noise issues. Also with micro-scaling, optical detection overcomes the increased parasitics without any sensitivity degradation, unlike capacitive detection. For hearing aids, along with sensitivity, battery life is another challenge. We propose the use of 1-bit front-end sigma-delta ADC for overall improved hearing aid power efficiency. Front-end interface based on envelope detection and synchronous detection schemes have also been designed. These interface circuits consume currents in microampere range from a 1.5V battery. Circuit techniques are used for maximizing linear range and signal handling with low supplies. The entire front end signal processing with Vertical Cavity Surface Emitting Laser (VCSEL) drivers, photodiodes, filters and detectors is implemented on a single chip in 0.35um CMOS process.

Alterações temporárias ou permanentes na audição podem ser encontradas nas orelhas submetidas a níveis elevados de pressão sonora. As mudanças temporárias induzidas nas orelhas protetizadas, quando estimuladas por suas próteses auditivas ajustadas na amplificação prescrita, foram avaliadas em um grupo de 25 pacientes após um período controlado (2 a 2 ½ h) de exposição ao ruído presente em um ambiente acústico comum. O estudo foi dividido em três etapas. Uma medida inicial foi realizada na primeira etapa para mensurar a magnitude das mudanças temporárias dos limiares auditivos, induzidas nas 42 orelhas (25 pacientes) durante um período contínuo de exposição ao ruído, com suas próteses auditivas ajustadas na amplificação prescrita. Na segunda etapa, essas 42 orelhas foram divididas em dois grupos distintos: as 22 orelhas protetizadas (13 pacientes) que apresentaram maior mudança temporária inicial nos limiares auditivos foram incluídas no Grupo Experimental e as 20 orelhas protetizadas (12 pacientes) que apresentaram menor mudança temporária inicial nos limiares auditivos foram incluídas no Grupo Convencional. Nesta etapa, as próteses auditivas, adaptadas nas 22 orelhas incluídas no Grupo Experimental, tiveram a sua amplificação reduzida por um período de 60 a 90 dias proposto para o \"treinamento\" das orelhas no uso cotidiano de suas próteses auditivas. Após este período de treino, a amplificação das próteses auditivas retornou ao nível prescrito. No Grupo Convencional, a amplificação prescrita das próteses auditivas adaptadas não foi alterada. Durante esta etapa, quatro medidas das mudanças temporárias induzidas nos limiares auditivos foram realizadas para os dois grupos nas mesmas condições de exposição ao ruído adotadas para a determinação da medida inicial. Uma última medida das mudanças temporárias induzidas nos limiares auditivos foi realizada na terceira etapa, também em idênticas condições. Esta última medida ocorreu em média 30/35 dias depois do término do treinamento, quando os pacientes do Grupo Experimental já faziam o uso cotidiano de suas próteses auditivas reajustadas na amplificação prescrita. A análise estatística de variância (ANOVA) comparou o comportamento das mudanças temporárias induzidas nos limiares auditivos nas três etapas do estudo. Para as orelhas incluídas no Grupo Experimental, foram verificadas alterações estatisticamente significantes (f<0,05) durante as etapas do estudo. As mudanças temporárias induzidas nos limiares auditivos das orelhas incluídas no Grupo Experimental aumentaram nos primeiros quinze a trinta e cinco dias após o inicio do treinamento. Com a continuidade do treinamento essas alterações foram gradualmente se reduzindo. As mudanças temporárias induzidas no final do treinamento (etapa pós-experimental) foram as menores observadas durante o estudo. A redução teve inicio nas freqüências abaixo de 1000 Hz e se extendeu na faixa de freqüência mais afetada nas orelhas protetizadas durante a exposição inicial ao ruído ambiente (250 a 2000 Hz). Para as orelhas incluídas no Grupo Convencional não foram constatadas alterações estatisticamente significantes (f>0,05) nas mudanças temporárias induzidas nos limiares auditivos quando avaliadas nas mesmas condições de exposição ao ruído ambiente. Entretanto, para as freqüências mais graves (250 Hz), foi verificada uma tendência a redução nestas alterações no decorrer do estudo / It is well known that the temporary threshold shift in hearing sensitivity is the most obvious hearing effect of the high level acoustic stimulation. Temporary threshold shifts induced in the aided ears were measured in 25 patients after the use of the hearing aids fitted in the prescribed gain during a controlled exposition time (2 a 2 ½ h) to an environmental noise. The study was performed in three phases. In the first phase a first measure of the temporary threshold shift was obtained for 42 aided ears (25 patients) in order to measure the initial amount of temporary threshold shift induced by the hearing aids fitted in the prescribed acoustic gain. In the second phase the ears were included into two study groups: The Experimental Group (EG) formed by 22 ears (13 patients) with greater temporary threshold shift in the initial measure and the Conventional Group(CG) , formed by 20 ears with the shorter temporary threshold shift in the initial measure . The hearing aids amplification in the 22 aided ears of the Experimental Group was reduced during the daily use for a \"training\" period of about 60 to 90 days, and after that was turned to the prescribed gain. The prescribed gain was not modified to the 20 ears of the Conventional Group. Four measure of temporary threshold shift were performed in the second phase when the patients included in the two groups were exposed to an environmental noise in the same conditions used to obtain the initial measure. The last measure (post-experimental phase) of the temporary threshold shift was performed in the same conditions , 30 days in average after the patients of Experimental Group had returned to use their hearing aids in the prescribed gain. In the Experimental Group, the analysis of the variance (ANOVA) showed significant differences(f<0,05) in the amount of induced temporary threshold shifts measured during the three phases of the study. Fifteen or thirteen five days after the training had begun the amount of temporary threshold shift increase, but with the continuous training it was gradually to reduced .In the end of the study, the last measure (post-experimental phase) was performed and the amount of temporary thresholds shift was very shorter. This reduction of temporary threshold shift was initially verified in the frequencies below 1000 Hz and at the end of the study all of the frequencies initially affected during the exposition time to the environmental noise (250 to 2000 Hz) were significantly reduced. In the ears included in the Conventional Group it was not verified temporary threshold shift statistically significant (f>0,05) in any moment, but in the low frequencies (250 Hz) it was noticed a gradually reduction of the amount of temporary threshold shift during the period of this study

Sound localization is a vital aspect of hearing for safe navigation of everyday environments. It is also an important factor in speech intelligibility. This ability is facilitated by the interaural level difference (ILD) cue, which arises from binaural hearing: a sound will be more intense at the nearer ear than the farther. In a hearing-impaired listener, this binaural cue may not be available for use and localization may be diminished. While conventional, bilateral, wide dynamic range compression (WDRC) hearing aids distort the interaural level difference by independently altering sound intensities in each ear, wirelessly-linked devices have been suggested to benefit this task by matching amplification in order to preserve ILD. However, this technology has been shown to have varying degrees of success in aiding speech intelligibility and sound localization. As hearing impairment has wide-ranging adverse impacts to physical and mental health, social activity, and cognition, the task of localization improvement must be urgently addressed. Toward this end, neural modelling techniques are used to determine neural representations of ILD cues for linked and unlinked bilateral WDRC hearing aids. Findings suggest that wirelessly-linked WDRC is preferable over unlinked hearing aids or unaided, hearing-impaired listening, although parameters for optimal benefit are dependent on sound level, frequency content, and preceding sounds. / Thesis / Master of Applied Science (MASc)