Neurological evidence indicates that instrumental musicians experience changes in the auditory system following skill acquisition and sensory training; yet, little is known about auditory neural plasticity in formally trained vocal musicians. Furthermore, auditory pitch discrimination and laryngeal control are recognized as essential skills for vocal musicians; however, the relationship between physiological variables, perceptual abilities, and vocal production is unclear. Electrophysiologic and psychoacoustic measures were used to examine pitch production accuracy as well as pre-attentive and active pitch discrimination between nonmusicians and two classes of musicians. Participants included 40 formally trained musicians (19 vocalists/21 instrumentalists) and 21 nonmusician controls. All were right-handed young adult females with normal hearing. Stimuli were harmonic tone complexes approximating the physical characteristics of piano tones and represented the mid-frequency range of the untrained female vocal register extending from C4 to G4 (F0 = 261.63-392 Hz). Vocal pitch recordings were spectrally analyzed to determine pitch production accuracy. Difference limens for frequency (DLFs) were obtained by an adaptive psychophysical paradigm. Pre-attentive auditory discrimination was assessed by auditory evoked potentials (AEPs), including the mismatch negativity (MMN). A standard tone (G4 = 392 Hz) and three deviants differing in frequency (1.5%, 3%, and 6% below) were presented in a multi-deviant paradigm. All musicians demonstrated superior pitch perception and vocal production compared to nonmusicians. Pitch perception and production accuracy did not significantly differ between vocalists and instrumentalists; however, pitch production accuracy was most consistent within the vocalist group. Music training appears to facilitate both auditory perception and vocal production regardless of music specialty. Pitch perception and production were correlated skills only for instrumental musicians. Vocalists demonstrated minimal variability for both skills so that perception and production were not correlated. These two skills may be independent abilities between which a relationship develops with training. AEP analysis revealed an influence of musical expertise on neural responses as early as 50 ms after onset of musically relevant stimuli. MMN responses indicate that vocal musicians as well as instrumental musicians have superior sensory memory representations for acoustic parameters of harmonic stimuli and imply that auditory neural sensitivity is developed by intense music training.

Made available in DSpace on 2015-03-26T13:44:25Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2476431 bytes, checksum: c677c5ea763b4c6c6871b352e0389ae9 (MD5) Previous issue date: 2011-03-02 / Starting from the premise that language is a form of social action, the main aim of this study is to examine how students of an Adults Education Program (AEP), from a public school located in a peripheral neighborhood of a city in Minas Gerais, build and take their social identities. Grounded in theories of Ethnomethodological Conversation Analysis (ECA) and in Interactional Sociolinguistics (IS), we analyze the linguistic and discursive choices of these students, observed from the talk-in-interaction in a focus groups, to identify how these students demonstrate membership in certain social categories. To collect the data, we used a focus group, through which students narrated their experiences of living in a peripheral neighborhood. After a detailed transcript of the data generated in the meetings with students, which was done according to the proposal from ECA, we analyzed it based on the concept of Sacks‟ Membership categorization (1992). Since the categorization processes are in use and in constant negotiations, we revealed, thus, students' discursive action, during interactions with one another, to build their identities through self-categorization and categorization. The results of this research indicate participants‟ orientation throughout the interaction, building, through speech, the identity of outsiders, ratifying the label assigned to them by those who occupy prestigious positions of power and by those who recognize themselves as the "good society", as Elias e Scotson (2000). By categorizing themselves as deviant, the participants seem to perceive their place in the city surveyed, but, they do not often accept this label passively: this generates reports of a conflictual relationship between these young people and the members of the so-called "good society". Thus, we conclude that through membership categorization, students build and assume the identity of outsiders, and that a description and categorization work is quite relevant to the study of the construction of social identities. / Partindo da premissa básica de que a linguagem é uma forma de ação social, o objetivo central deste estudo é analisar como alunos da Educação de Jovens e Adultos (EJA) de uma escola pública localizada em um bairro periférico de uma cidade do interior de Minas Gerais constroem e assumem as suas identidades sociais. Embasados em teorias da Análise da Conversa Etnometodológica (ACE) e da Sociolinguística Interacional (SI), analisamos as escolhas linguístico-discursivas desses alunos, observadas a partir da fala-em-interação em grupos focais, para verificar como esses estudantes demonstram pertencimento a determinadas categorias sociais. Para coleta de dados, utilizamos a técnica do grupo focal, através da qual os discentes narram a experiência de morar em um bairro periférico. Após uma minuciosa transcrição dos dados gerados nos encontros com os estudantes, feita de acordo com a proposta da ACE, fizemos uma análise baseada no conceito de Categorização de Membros, de Sacks (1992). Uma vez que os processos de categorização estão em uso e negociações constantes, revelamos, assim, a ação discursiva dos estudantes, durante interações entre si, para a construção de suas identidades por meio de autocategorização e categorização. Os resultados desta pesquisa apontam a orientação dos participantes durante a interação, os quais constroem, através da fala, a identidade de outsiders, ratificando o rótulo que lhes é atribuído por aqueles que ocupam posições de prestígio e poder e que se reconhecem como a boa sociedade , os quais chamaremos de estabelecidos, assim como Elias e Scotson (2000). Ao se categorizarem como desviantes, os estudantes de EJA demonstram perceber o lugar deles na cidade pesquisada, mas, muitas vezes, não aceitam passivamente tal rótulo, o que gera relatos de uma relação conflituosa entre esses jovens e os estabelecidos. Assim, ao concluir que, através da categorização de membros, os estudantes constroem e assumem a identidade de outsiders, demonstramos que o trabalho de descrição e de categorização de membros é bastante pertinente para o estudo da construção de identidades sociais.

This project is conducted in cooperation with Hexicon AB, which is a Swedish design and engineering company developing floating two-turbine platforms for offshore wind power.The study aims to investigate the optimal placement of Hexicon AB’s platforms in an offshore wind farm with respect to the Annual Energy Production (AEP). Wind farm layout optimization is a complex problem and it has been approached by the development of calculation and optimization programs in Matlab. The analytical Jensen wake model has been utilized for calculation of AEP and important inputs to the program have been turbine parameters and site specific conditions. The optimization strategy used is a multi-stage algorithm where the gradient-based local search algorithm Fmincon has been used in combination with a version of the heuristic genetic algorithm. The developed programs have been tested and evaluated through a case study. Included in the case study is also a brief financial evaluation regarding how different scenarios in electricity export price and costs for cabling could affect the feasibility of the optimized layouts. Concluded from the project is that the developed programs can be used to investigate the optimal placement of floating two-turbine platforms with respect to AEP. In the case study it was found that the optimized layout obtained a wind farm efficiency of around 4% more than for the conventional staggered layout that was tested. What is also emphasized is that the feasibility of the optimized layouts obtained from the program is quite sensitive toward changes in future electricity export price and costs for cabling and installation. Hence, it is important to perform a careful financial analysis in order to draw conclusions regarding what layout is the better option for a specific situation. / Dagens utbyggnad av vindkraft sker i allt större utsträckning genom etablering av vindkraftparker. De främsta fördelarna med att placera vindkraftverken i parker är att de höga fasta kostnaderna fördelas på flera kraftverk samt att man kan beställa ett flertal enheter samtidigt och därigenom minska kostnaden per installerad Megawatt (MW). För att ytterligare kunna öka vinsten på investeringen är det viktigt att undersöka optimal inbördes placering av vindkraftverken för att erhålla en så hög energiproduktion som möjligt. Det finns många studier gjorda inom området och ett flertal programvaror utvecklade. Dock finns det endast ett fåtal studier som har inriktat sig specifikt på flytande vindkraftverk. Detta arbete är utfört i samarbete med Hexicon AB, vilket är ett Stockholmsbaserat ingenjörsföretag som utvecklar en patenterad teknik för plattformar avsedda för flytande vindkraft. Det unika med Hexicon ABs patenterade teknik är att två vindkraftverk är placerade på en gemensam plattform. Denna teknik gör det möjligt för plattformen att anpassa sig till vindriktningen vilket ger en ökning av kraftverkens energiutbyte. Då det inte finns några utvecklade optimeringsmetoder för flytande plattformar som kan anpassa sig efter vindriktning är syftet för denna studie att undersöka den optimala inbördes placeringen av Hexicon ABs plattformar i en vindkraftpark. Eftersom vindkraftsoptimering är ett komplicerat problem som bland annat är icke-linjärt och icke-konvext så finns det ingen exakt lösning tillgänglig för problemet. Komplexiteten gör även många förenklingar och antaganden nödvändiga för att kunna bearbeta problemet. I detta projekt har sambandet mellan årlig elproduktion och inbördes placering av plattformarna undersökts genom att ett kalkylerings- och optimeringsprogram utvecklats i programvaran Matlab. För att kunna undersöka den optimala inbördes placeringen av vindkraftverken är det viktigt att förstå hur vindkraftverken påverkas av att placeras tillsammans i en park. För att göra detta så behövs en modell för att beskriva den så kallade vaken som uppstår bakom respektive vindkraftverk. Detta gjordes genom att använda den analytiska Jensen vakmodellen, vilket är den vanligaste modellen att använda för optimeringssyften. Beräkningen av elproduktion gjordes baserat på given information angående turbinparametrar samt specifika förhållanden på platsen för vindparken. För det utvecklade optimeringsprogrammet användes en tvåstegsalgoritm där den gradientbaserade algoritmen Fmincon utgjorde den centrala delen. Fmincon är en effektiv algoritm för lokal optimering som finns tillgänglig i Matlab. För att generera bra startgissningar till den lokala optimeringen användes en version av en heuristisk genetisk algoritm som komplement till Fmincon. Denna algoritm bygger på samma princip som processen för naturligt urval i evolutionssammanhang där de bäst lämpade individerna för vidare sina egenskaper till nästa generation. För att ytterligare förbättra algoritmen kompletterades den även med ett moment av slumpmässighet. För att testa och utvärdera de utvecklade programmen genomfördes en fallstudie. I denna studie optimerades 50 stycken olika heuristiska startgissningar. De 20 bäst presterande konfigurationerna valdes ut för vidare analys där de blev utvärderade med avseende på olika scenarion för elpris samt kostnad för elektrisk infrastruktur. Detta för att undersöka hur den optima placeringen eventuellt skulle kunna påverkas av osäkerheter i dessa faktorer. Den genomförda fallstudien indikerade att de utvecklade programmen kan användas för att undersöka den inbördes optimala placeringen av vindkraftverk med avseende på elproduktion. Den ekonomiska utvärderingen indikerade även att den optimala placeringen var känslig för olika scenarion där elpris och kostnader för infrastruktur varierades och att detta kunde påverka lönsamheten för investeringen. Det ska därför betonas att det anses vara viktigt att utföra en mer noggrann ekonomisk utvärdering av de optimerade konfigurationerna för att undersöka vilken positionering som är mest lämplig för en viss situation.

Abstract Purpose: To compare the frequency specific Cortical Auditory Evoked Potential (CAEP) and the chirp-evoked 40 Hz Auditory Steady State Response (ASSR) with equivalent residual noise levels for behavioural threshold prediction in adults with normal hearing and with SNHL. Method: The study tested 23 adults with normal hearing and 20 adults with SNHL. The participants were aged between 18–65 years. A repeated measures within- participant descriptive design was used to collect the quantitative data. The participants underwent behavioural pure tone, CAEP and ASSR testing on the same day. Results: Similar CAEP difference scores across frequencies for the participants with normal hearing (mean=12.32-14.40 dB) and with SNHL (mean=10.00-16.47 dB) were measured. However, for the ASSR difference scores across frequencies slightly smaller difference scores were measured for the participants with SNHL (mean=10.17-17.30 dB) than for the participants with normal hearing (mean=11.74- 17.14 dB). CAEP thresholds were significantly closer to the behavioural pure tone thresholds at 500 (p=0.028; mean absolute difference 14.40 dB) and 2000 (p=0.016; mean absolute difference 12.56 dB) Hz for participants with normal hearing. In participants with sensorineural hearing loss, CAEP and ASSR thresholds were measured at similar sensation levels and were not statistically different (p>0.05). Conclusion: For the purpose of threshold estimation, representing the auditory function to the level of the auditory cortex the CAEP was closer to the behavioural hearing thresholds than the 40 Hz ASSR at all frequencies except at 4000 Hz, regardless of the hearing sensitivity. Keywords: Auditory steady state response (ASSR), Cortical auditory evoked potential (CAEP), Auditory evoked potential (AEP), Residual noise, Signal to noise ratio (SNR), objective threshold estimation, awake adults. / Dissertation (MA (Audiology))--University of Pretoria, 2019. / Speech-Language Pathology and Audiology / MA Audiology / Unrestricted

Transitioning to a low-carbon energy system includes deploying renewables such as wind power, which has been installed in Sweden since the 1980s. After a 20 to 25-year lifetime, a wind turbine´s end-of-life options come into play, therefore many of the turbines deployed in Sweden prior to 2011 will reach this mark by 2035. To utilize a site´s wind resource in the best possible way, full repowering is considered in an assessment of seven case studies in Swedish municipalities with the highest deployed pre-2011 wind power capacity. Each case study uses various turbine models to evaluate full repowering scenarios. The most profitable scenarios are estimated through the investment over production (I/P) value and the break-even electricity price. The identified municipalities’ comprehensive plans are reviewed in terms of repowering strategies and wind power deployment guidelines. Only three out of seven investigated municipalities consider repowering in comprehensive plans, with Gotland being best prepared in terms of repowering strategies. Strömsund and Eslöv mention repowering in their comprehensive plans with no specific guidelines. Restrictive policies were identified in the municipality of Laholm, where the maximum total height of turbines is 150m, decreasing the potential annual energy production of an analyzed case study by 64%. The municipalities of Falkenberg, Laholm, Piteå, and Åsele do not include repowering in their comprehensive plans. All the simulated repowering scenarios increased the annual energy production of the identified sites by up to 73%, lowered the number of turbines by up to 70%, decreased the wake losses by up to 77%, and decreased the noise level by 10% while increasing the potential shadow flicker by 19%. The results of the study indicate a possible divide between the intention of the municipalities of Eslöv, Strömsund, and Åsele to maximize energy production from wind power at each exploited site on the one hand and the business cases that developers face on the other. The results suggest the turbines which increase energy production the most at already developed sites, are not necessarily the ones with the lowest investment over production (I/P) value or the lowest break-even electricity price.

La consommation de poisson et de mammifères marins représente une source importante d’acides gras oméga-3 connus pour leurs effets bénéfiques sur le développement des fonctions cérébrales et notamment, sur le développement du système visuel. Afin de tester l’hypothèse selon laquelle l’exposition prénatale aux acides gras oméga-3 a des effets bénéfiques à long terme, nous avons examiné les fonctions visuelles chez des enfants Inuits d’âge scolaire exposés à de grandes quantités d’oméga-3 durant la période de gestation. Des enfants Inuits (n = 136; moyenne d’âge = 11.3 ans) du nord du Québec (Nunavik) ont participé à cette étude. Un protocole de potentiels évoqués visuels (PEVs) utilisant des stimuli en couleur et en mouvement a été employé afin d’appréhender les réponses parvo- et magnocellulaires respectivement. Les concentrations d’acide docosahexaénoïque (ADH) ont été mesurées à la naissance à partir du sang de cordon ombilical et au moment du testing, reflétant ainsi les expositions pré- et post-natales. Les relations entre les niveaux sanguins d’ADH et les PEVs ont été examinées à l’aide d’analyses de régression multiples, en tenant compte des contaminants environnementaux et d’autres variables potentiellement confondantes. Aucune association significative n’a été trouvée en ce qui concerne les stimuli de mouvement. Cependant, après ajustement pour les covariables, les concentrations d’ADH à la naissance étaient associées à une latence plus courte des composantes N1 et P1 des PEVs couleur. Notre étude démontre, pour la première fois, des effets bénéfiques de l’exposition prénatale à l’ADH sur le système parvocellulaire à l’âge scolaire. / Fish and sea mammals consumption is an important source of omega-3 fatty acids, known for their beneficial effects on human brain development. Several lines of evidence indicate that omega-3 fatty acids are beneficial especially for the development of the visual system. However, the long-term effect of prenatal exposure to omega-3 fatty acids on human visual development is unknown. This question was addressed using visual evoked potentials (PEVs) to study a cohort of school-age Inuit children (n = 136; mean age = 11.3 years old) from Arctic Quebec (Nunavik) who received high levels of omega-3 intake during gestation. PEV protocols using color and motion-onset stimuli were used to assess the parvocellular and magnocellular responses, respectively. Concentrations of the omega-3 fatty acid DHA were measured at birth in the umbilical cord and at the time of testing, reflecting pre- and post-natal exposure, respectively. Relations between omega-3 and VEPs were assessed by multivariate regression analyses, taking into account environmental contaminants and other potential confounding variables. No significant associations were found with motion-onset VEPs. However, after adjustment for covariables, cord blood concentrations of DHA were associated with a shorter latency of the N1 and P1 components of the color VEPs. Our study suggests beneficial effects of DHA on the visual parvocellular system at school age. This is the first study supporting the longlasting beneficial effects of prenatal exposure to DHA.

Les antennes présentes dans la plupart des systèmes communicants comme les véhicules automobiles, les avions et les trains se multiplient et sont soumises à une contrainte d’intégration de plus en plus sévère. De nombreuses techniques de miniaturisation d’antennes existent et passent toutes par un compromis entre la taille et les performances (bande passante et/ou rendement de rayonnement). Pour les systèmes cités ci-dessus, les antennes sont souvent placées devant ou à proximité d’un réflecteur métallique (toit de véhicule, carlingue d’aéronef). Dans ce cas, l’épaisseur de système antennaire est une contrainte majeure et les métamatériaux de type Conducteur Magnétique Artificiel (CMA) ouvrent des perspectives intéressantes grâce à leurs propriétés électromagnétiques non conventionnelles. Cependant, pour les applications sub-GHz (RFID, LTE, PMR…), les CMA sont limités par les dimensions des cellules unitaires nécessaires à leur mise en œuvre (λg/4) ainsi que leur bande réduite de fonctionnement. Réduire leurs dimensions permet de rendre leur utilisation compatible avec le contexte des antennes miniatures intégrées. Ajouter l’agilité fréquentielle permet de palier le problème de la bande passante réduite dans le cas des antennes et des CMA miniaturisés en ajustant le fonctionnement du système antennaire sur une large bande passante. Cette thèse de doctorat propose d’étudier et de développer un nouveau système antennaire à faible profil composé d’une antenne miniature associée à une métasurface compacte reconfigurable en fréquence et compatible avec le standard NB-IoT dans la bande basse LTE (700 MHz – 960 MHz). / Antennas are now very integrated in several connected systems like cars, airplanes and trains. Many antenna miniaturization techniques exist and all go through a compromise between size and performance (bandwidth and/or radiation efficiency). For the systems mentioned above, the antennas are often placed near a metallic reflector (vehicle roof, aircraft cabin). Within this context, Artificial Magnetic Conductors (AMC) present an attractive reflector for low profile antennas which can take advantage of intrinsic zero reflection phase response to boost antenna performance without the need for thick quarter wave backplane. However, for sub-GHz applications (RFID, LTE, PMR ...), AMC are limited by the size of the unit cells necessary for their implementation (λg/4) as well as their reduced operating bandwidth. AMC miniaturization makes their use compatible with small antennas. Adding tunability restores the possibility of adjusting the operating frequency over a large bandwidth. This PhD thesis proposes to study and develop a new electrically small, low-profile antenna based on miniaturized and tunable AMC for the NB-IoT standard in low LTE band (700 MHz – 960 MHz).

La consommation de poisson et de mammifères marins représente une source importante d’acides gras oméga-3 connus pour leurs effets bénéfiques sur le développement des fonctions cérébrales et notamment, sur le développement du système visuel. Afin de tester l’hypothèse selon laquelle l’exposition prénatale aux acides gras oméga-3 a des effets bénéfiques à long terme, nous avons examiné les fonctions visuelles chez des enfants Inuits d’âge scolaire exposés à de grandes quantités d’oméga-3 durant la période de gestation. Des enfants Inuits (n = 136; moyenne d’âge = 11.3 ans) du nord du Québec (Nunavik) ont participé à cette étude. Un protocole de potentiels évoqués visuels (PEVs) utilisant des stimuli en couleur et en mouvement a été employé afin d’appréhender les réponses parvo- et magnocellulaires respectivement. Les concentrations d’acide docosahexaénoïque (ADH) ont été mesurées à la naissance à partir du sang de cordon ombilical et au moment du testing, reflétant ainsi les expositions pré- et post-natales. Les relations entre les niveaux sanguins d’ADH et les PEVs ont été examinées à l’aide d’analyses de régression multiples, en tenant compte des contaminants environnementaux et d’autres variables potentiellement confondantes. Aucune association significative n’a été trouvée en ce qui concerne les stimuli de mouvement. Cependant, après ajustement pour les covariables, les concentrations d’ADH à la naissance étaient associées à une latence plus courte des composantes N1 et P1 des PEVs couleur. Notre étude démontre, pour la première fois, des effets bénéfiques de l’exposition prénatale à l’ADH sur le système parvocellulaire à l’âge scolaire. / Fish and sea mammals consumption is an important source of omega-3 fatty acids, known for their beneficial effects on human brain development. Several lines of evidence indicate that omega-3 fatty acids are beneficial especially for the development of the visual system. However, the long-term effect of prenatal exposure to omega-3 fatty acids on human visual development is unknown. This question was addressed using visual evoked potentials (PEVs) to study a cohort of school-age Inuit children (n = 136; mean age = 11.3 years old) from Arctic Quebec (Nunavik) who received high levels of omega-3 intake during gestation. PEV protocols using color and motion-onset stimuli were used to assess the parvocellular and magnocellular responses, respectively. Concentrations of the omega-3 fatty acid DHA were measured at birth in the umbilical cord and at the time of testing, reflecting pre- and post-natal exposure, respectively. Relations between omega-3 and VEPs were assessed by multivariate regression analyses, taking into account environmental contaminants and other potential confounding variables. No significant associations were found with motion-onset VEPs. However, after adjustment for covariables, cord blood concentrations of DHA were associated with a shorter latency of the N1 and P1 components of the color VEPs. Our study suggests beneficial effects of DHA on the visual parvocellular system at school age. This is the first study supporting the longlasting beneficial effects of prenatal exposure to DHA.

A ce jour, six millions de français sont atteints de troubles de l'audition. Face à ce problème de santé publique, des outils performants d'exploration de la fonction auditive sont indispensables. La Speech ABR (Speech Auditory Brainstem Response ou Réponse du tronc cérébral auditif à la parole) est un outil prometteur, comme marqueur électrophysiologique fin de l'encodage neuronal de la parole. Cependant, sa méthodologie reste peu développée, son origine neuronale incertaine et elle n'a jamais été enregistrée chez le malentendant porteur d'aides auditives. Le premier axe de cette thèse porte sur les générateurs neuronaux de la Speech ABR. Le développement d'une méthodologie de recueil topographique de cette réponse jusqu'alors décrite comme strictement sous-corticale, a d'abord suggéré la possibilité d'un générateur cortical. Une étude en stéréo-électroencéphalographie a ensuite confirmé l'existence d'une activité Speech ABR dans les cortex auditifs primaires bilatéraux. Ce résultat apporte un éclairage nouveau sur la représentation des sons de parole par système nerveux auditif. Le second axe concerne l'étude de la Speech ABR chez le malentendant appareillé. Après avoir développé une méthodologie de stimulation acoustique directement au travers des aides auditives, nous avons étudié la plasticité neuronale induite par le port d'aides auditives. Les résultats montrent une amélioration de l'identification des phonèmes amplifiés, liée à une représentation corticale modifiée et à un encodage fréquentiel rééquilibré. Ces toutes premières preuves de plasticité neuronales dès les 4 premiers mois d'utilisation des aides auditives ouvrent de nouveaux espoirs thérapeutiques / To date, six million French are hearing impaired. To address this public health issue, efficient tools for exploration of the hearing function are essentials. Speech ABR (Speech Auditory Brainstem Response) is a promising tool, being a fine electrophysiological marker of the neuronal encoding of speech. Though, its methodology remains underdeveloped, its neural origin is still uncertain, and it has never been recorded in hearing aid users. The first axis of this thesis focuses on the neural generators of Speech ABR. The development of a methodology for recording topographies of this response, up to now described as strictly subcortical, first suggested the possibility of a cortical generator. A stereo-electroencephalography study then confirmed the existence of Speech ABR activity in bilateral primary auditory cortices. This result sheds a new light on the representation of speech sounds within the auditory nervous system. The second axis concerns the study of Speech ABR in hearing aid users. After having developed a methodology of acoustic stimulation directly through hearing aids, we investigated neural plasticity induced by hearing aid use. Results show an improvement in the identification of amplified phonemes, linked to an altered cortical representation and a rebalanced frequency encoding. This very first evidence of neural plasticity as soon as the first four months of hearing aid use opens up new therapeutic hopes