The objective of this doctoral thesis is to study three different innovative noise control techniques in ducts namely: acoustic metamaterials, porous absorbers and microperforates. There has been a lot of research done on all these three topics in the context of duct acoustics. This research will assess the potential of the acoustic metamaterial technique and compare to the use of conventional methods using microperforated plates and/or porous materials.  The objective of the metamaterials part is to develop a physical approach to model and synthesize bulk moduli and densities to feasibly control the wave propagation pattern, creating quiet zones in the targeted fluid domain. This is achieved using an array of locally resonant metallic patches. In addition to this, a novel thin slow sound material is also proposed in the acoustic metamaterial part of this thesis. This slow sound material is a quasi-labyrinthine structure flush mounted to a duct, comprising of coplanar quarter wavelength resonators that aims to slow the speed of sound at selective resonance frequencies. A good agreement between theoretical analysis and experimental measurements is demonstrated. The second technique is based on acoustic porous foam and it is about modeling and characterization of a novel porous metallic foam absorber inside ducts. This material proved to be a similar or better sound absorber compared to the conventional porous absorbers, but with robust and less degradable properties. Material characterization of this porous absorber from a simple transfer matrix measurement is proposed.The last part of this research is focused on impedance of perforates with grazing flow on both sides. Modeling of the double sided grazing flow impedance is done using a modified version of an inverse semi-analytical technique. A minimization scheme is used to find the liner impedance value in the complex plane to match the calculated sound field to the measured one at the microphone positions. / <p>QC 20160923</p>

Abstract Interacting many-body problems are central to most fields of physics. In condensed matter physics, the systems of interest consists of a number of bodies on the order of Avogadro's constant, ~10²³. The precise modeling of such systems is usually impossible. Under certain circumstances however, even these problems can become tractable. One such circumstance is that of a Fermi liquid. At sufficiently low temperatures, in describing the dynamics of a system of interacting fermions, it is possible to forgo description of the fermions themselves, and instead concentrate on the collective excitations of the entire fermion system. These collective excitations are called quasiparticles. In this thesis we study two phenomena related to the motion of objects in a Fermi liquid. First, we study the transmission of transverse oscillations through a thin film of normal Fermi liquid. The dynamics of normal Fermi liquid are described by Landau's Fermi liquid theory. Landau's theory predicts the existence of new modes of sound under conditions where sound ordinarily would not propagate. Using the equations of motion for the Fermi liquid quasiparticles, we calculate the linear response of a Fermi liquid film to the transverse oscillations of a planar substrate under a wide range of conditions. We present the linear response in terms of the film's acoustic impedance and study the effects of quasiparticle collisions and of the Fermi liquid interactions. The second phenomenon we study is the supercritical motion of a wire in a superfluid Fermi liquid. The prevailing assumption is that if the velocity of an object moving in a superfluid Fermi liquid surpasses a characteristic critical velocity, the object experiences a sudden onset of viscous forces. This viscosity is caused by the escape of quasiparticles, produced by pair breaking on the surface of the object, into the surrounding superfluid. We study Andreev reflection of the quasiparticles by the surrounding superfluid flow field, and modifications to the flow caused by pair breaking, as possible mechanisms for low-dissipation motion above the critical velocity. / Original publications The original publications are not included in the electronic version of the dissertation. Kuorelahti, J. A., Tuorila, J. A., &amp; Thuneberg, E. V. (2016). Fermi liquid theory applied to a film on an oscillating substrate. Physical Review B, 94(18). https://doi.org/10.1103/physrevb.94.184103 Kuorelahti, J. A., &amp; Thuneberg, E. V. (2018). Two-parameter boundary condition applied to transverse acoustic impedance of a Fermi liquid. Journal of Physics: Conference Series, 969, 12010. https://doi.org/10.1088/1742-6596/969/1/012010 http://jultika.oulu.fi/Record/nbnfi-fe2018060425173 Kuorelahti, J. A., Laine, S. M., &amp; Thuneberg, E. V. (2018). Models for supercritical motion in a superfluid Fermi liquid. Physical Review B, 98(14). https://doi.org/10.1103/physrevb.98.144512 http://jultika.oulu.fi/Record/nbnfi-fe2018112148794

L’étude présentée dans cette thèse se situe dans le domaine de l’acoustique modale des conduits avec des parois absorbantes et un écoulement moyen. Nous considérons une source de bruit en amont avec une fréquence fixe. Avec cela, nous étudions les modes propres acoustiques du conduit en terme de nombre d’onde qui sont présents.Avec cette étude, nous contribuons à la meilleure compréhension de la propagation du sondans ce type de configuration. Parmi les applications, il y a la réduction du bruit des moteurs des aéronefs.Une analyse numérique par la méthode pseudospectrale de collocation, sur la base de polynômes de Chebyshev, a été mise en ouvre pour obtenir le spectre des modes, dans un domaine transversal.Pour cela, deux programmes ont été utilisés : le programme FiEStA, qui a été développé dans le cadre de cette thèse, et qui résout les équations d’Euler linéarisées, en considérant un problème à une ou deux une ou deux dimensions. D’autre part, le programme MAMOUT, a été utilisé pour résoudre les équations de Navier-Stokes linéarisées, pour étudier plus spécifiquement les effets de la viscosité.Avec ces outils, on a constaté les effets de trois paramètres : lorsque le rapport d’aspect augmente, la densité des modes, en particulier des modes propagatifs, se développe également.Quand le nombre de Mach de l’écoulement moyen augmente, on observe les effets suivants sur les valeurs propres : un déplacement vers la partie réelle négative, une amplification de leur valeur absolue et un déplacement vers les modes d’indice inférieur. Le profil d’écoulement moyen induit aussi un déplacement dans les valeur propres, pas facilement prévisible. Il modifie également la forme des fonctions propres ; ce qui est notamment visible pour le mode d’onde plane. Les changements d’impédance induisent un échange cyclique de valeurs propres entre les valeurs de parois rigides des modes consécutifs. Avec certaines valeurs d’impédance, les modes acoustiques de paroi apparaissent. Ils sont caractérisés par la forme exponentielle de leurs fonctions propres.En plus des modes acoustiques, il existe des modes hydrodynamiques de surface qui se sont révélés avec quelques valeurs d’impédance et forme et nombre de Mach de l’écoulement moyen. Pour un ensemble de données de référence, ces modes ont été étudiés. L’impédance a été considérée avec un modèle basé sur des données de la littérature, tout comme le profil d’écoulement moyen.Un mode hydrodynamique a été trouvé. Avec certaines valeurs de la fréquence, l’ensemble des paramètres donne lieu à une instabilité. En utilisant le critère Briggs Bres pour la stabilité,l’instabilité a été jugée absolue.À partir du comportement des modes avec différentes valeurs de l’impédance, et conformément aux résultats publiés, nous avons défini la condition que le spectre doit remplir pour réduire autant que possible le bruit. C’est cela qu’on appelle l’impédance optimale. Nous avons calculé cette valeur pour différents fréquences et écoulements moyens. / The study presented in this thesis is within the domain of modal acoustics of lined ducts withgrazing flow. We consider an upstream source of noise with a fixed frequency, within a lined duct.From this, we study the eigenmodes in terms of wavenumber that are present in this system.With this study, we contribute to the better understanding of sound propagation in thedescribed configuration. Within its main applications, we can find the noise reduction fromaeroengines.A numerical analysis with the pseudospectral collocation method, based on Chebyshevpolynomials was used to obtain the spectrum of modes within the duct, in a domain transversalto the mean flow. For this, two programs were used: On one hand, within the frame of this thesis,the program FiEStA was developed. It solves the linearized Euler Equations, considering eitherone or two dimensions of the transversal plane. On the other hand, the already existing programMAMOUT was used for verification and to solve also the linearized Navier-Stokes Equations toobserve the effects of viscosity.With these tools, the first result was to notice the effects of three parameters: When theaspect ratio grows, the density of modes in the spectrum grows also. In particular, we havemore propagative modes. As the mean flow Mach number grows, we observe these effects on theeigenvalues: a displacement to the negative real part, a slight amplification of their absolute valueand a displacement towards the modes of lower index. The difference in mean flow profile inducesanother displacement in modes, not easily predictable. It changes also the shape of eigenfunctions,which is clearly seen for the planewave mode. The impedance changes induce a cyclic exchange ofeigenvalues from their hard wall value to the hard wall value of a consecutive mode. The changeof eigenfunction is gradually change in wavelength, to obtain the shape of the destination mode.With some impedance values, a pair of modes, called the acoustic surface modes arise. They arecharacterized by the exponential shape of their eigenfunctions.Besides these acoustic surface modes, there are also a pair of hydrodynamic surface modeswhich come to light with some values of impedance and shape and Mach number of the meanflow. With a benchmark data, these modes were studied. The impedance was considered from themodel of a measured liner while the mean flow profile was taken from experimental values. Withthis, the hydrodynamic mode was found. With specific values of frequency, the set of parametersgives rise to an instability. Using the Briggs-Bers criterion for stability, the instability was foundto be absolute for a given frequency.From the comportment of modes with different values of impedance, and in accordance withpublished results, we defined the condition that the spectrum has to fulfill to reduce as much aspossible the upstream noise. This is what we called the optimal impedance. We obtained it forseveral flow profiles and frequencies, in both 1D and 2D domains.

A avaliação da integridade do sistema tímpano-ossicular é um pré-requisito para que o processo de diagnóstico audiológico infantil possa ser concluído com precisão, assim, muito têm se discutido em relação aos procedimentos utilizados na prática clínica para definir a presença ou ausência de problema condutivo. Nesse sentido, as medidas de imitância acústica de banda larga mostram-se como uma opção para o avanço na área. Diante disso, surgiu o interesse em ampliar os conhecimentos e trazer as características das medidas de imitância acústica de banda larga nas diferentes condições de orelha média. O objetivo do estudo foi caracterizar as medidas de imitância acústica de banda larga com os estímulos tom puro e chirp em crianças com perda auditiva sensorial de grau severo e profundo e diferentes padrões timpanométricos. Foram avaliadas 187 orelhas de 98 crianças na faixa etária de seis a 60 meses de idade, subdivididas em grupos de acordo com a pressão e compliância obtidas na timpanometria com sonda de 226 Hz. As medidas de imitância acústica de banda larga foram realizadas por meio do sistema de medidas do Acoustics\' Middle-Ear Power Analyzer - MEPA, versão 5.0, utilizando os estímulos tom puro e chirp, com faixa de frequência de 211 a 6000 Hz. Os valores de compliância e pressão obtidos na timpanometria convencional foram correlacionados às medidas de imitância acústica de banda larga, adotando-se testes estatísticos apropriados, com nível de significância de 0,05. Os resultados obtidos evidenciaram o efeito das faixas de frequência (grave, média e aguda) em todas as medidas analisadas, com exceção do delay da reflectância. Foi constatada influência de pressões correspondentes a -100 daPa ou mais negativas e também para pressões positivas acima de 25 daPa, e compliâncias menores que 0,2 ml nas medidas de imitância acústica de banda larga. Além disso, houve diferença significante entre os estímulos tom puro e chirp para frequências baixas para a absorvância e magnitude da impedância, com maior reflexo da variação dos valores de compliância e pressão nos resultados obtidos com estímulo chirp. Conclui-se que as características das medidas de imitância acústica de banda larga estão relacionadas à condição de orelha média e a frequência do estímulo teste. Para o delay da reflectância observou-se uma ampla variabilidade entre frequências ao analisar os grupos subdivididos pela pressão e também na frequência de 258 Hz ao analisar os grupos subdivididos pela compliância. / The evaluation of the integrity of the tympanic-ossicular system is a prerequisite for the child audiology diagnostic process to be completed accurately, thus, much has been discussed in relation to the procedures used in clinical practice to define the presence or absence of conductive problems. Hence, the wideband acoustic immittance measurements show to be an option to the advance in the field. As a result, the interest in expanding the knowledge and bringing the characteristics of wideband acoustic immittance measurements in the different conditions of middle ear, emerged. This study aimed at characterizing the wideband acoustic immittance measurements using pure and chirp stimuli in children presented with severe and profound sensorineural hearing loss and different tympanometric standards. 187 ears of 98 children in the age range six-sixty months, subdivided into groups according to pressure and compliance achieved through tympanometry with a 226 Hz probe, were assessed. Wideband acoustic immittance measurements were performed by the measuring system of the Acoustics\' Middle-Ear Power Analyzer - MEPA, version 5.0, using pure and chirp tone stimuli, in a frequency ranging from 211 to 6000 Hz. The values of compliance and pressure obtained through conventional tympanometry were correlated with wideband acoustic immittance measures, by applying suitable statistical tests, with a 0.05 significance level. The results achieved evidenced the effect of frequency bands (low, medium and high) in all measures examined, with the exception of the reflectance delay. The Influence of pressures -100 daPa or more negative ones and also in positive pressures above 25 Pa, and compliance lower than 0.2 ml in the wideband acoustic immittance measurements, was verified. In addition, there was a significant difference between pure tone and chirp stimuli at low frequencies for impedance absorbance and magnitude, with a greater reflex of the variation of compliance and pressure values in the results obtained with the chirp stimulus. It is concluded that the characteristics of broadband acoustic immittance measures are related to the condition of middle ear condition and the frequency of the test stimulus. For Reflectance delay, a wide variability between frequencies was observed when analyzing the groups subdivided by pressure and also in the frequency of 258 Hz, when analyzing the groups subdivided by compliance.

Introdução: A apneia obstrutiva do sono (AOS) provoca modificações na arquitetura normal do sono, fragmentando-o de forma crônica com hipóxias intermitentes levando, a longo prazo, a sérias consequências na saúde. Acredita-se que a ocorrência de eventos respiratórios durante o sono como apneia e hipopneia pode prejudicar o mecanismo de transdução da orelha interna e a transmissão de impulsos nervosos ao longo da via auditiva que são altamente dependentes do fornecimento do oxigênio. Contudo, essa associação não se encontra bem estabelecida na literatura. Adicionalmente, sujeitos com AOS poderiam apresentar alterações na função de transferência acústica da orelha média devido ao desequilíbrio pressórico existente nas vias aéreas superiores durante o sono, característico da fisiopatologia da doença. Objetivo: Comparar os achados da avaliação auditiva entre os indivíduos portadores e não portadores de AOS. Método: A casuística foi composta por 38 adultos do sexo masculino, média de idade de 35,8 (±7,2) e foram divididos em quatro grupos experimentais pareados por idade e índice da massa corpórea. Os grupos foram classificados com base na polissonografia em: controle (n=10), AOS leve (n=11), AOS moderada (n=8) e AOS grave (n=9). Todos os sujeitos do estudo negaram história pregressa de risco para perda auditiva. Todos os sujeitos foram submetidos à audiometria convencional, timpanometria, pesquisa de reflexos acústicos ipsi e contralaterais, imitância acústica de banda larga com estímulo clique de 226 a 8000 Hz para obtenção da energia de absorvância (EA), emissões otoacústicas por produto de distorção e potenciais evocados auditivos de tronco encefálico. Os resultados foram submetidos às análises estatísticas e o nível de significância adotado foi de 5% para todos os testes. Resultados: As medidas da EA não mostraram diferença significante entre os grupos quando considerados somente o fator grupo (sem AOS, AOS leve, moderada e grave). Para o efeito de interação entre os fatores grupo e frequência, o valor da média da EA do grupo com AOS de grau moderado foi significativamente maior do que do grupo com AOS de grau leve (p=0,003) em 8000 Hz. O grupo com AOS de grau grave apresentou menores valores das médias das amplitudes das EOAPD quando comparados aos dos grupos controle, AOS de grau leve e AOS de grau moderado (p=0,02, p=0,03 e p=0,01, respectivamente). Não houve diferença significante nos valores das latências absolutas das ondas I, III e V, e interpicos I-III, III-V e I-V entre os grupos. Observou-se associação entre a presença da AOS e alteração da latência absoluta da onda V (p=0,03). Foi observada associação entre AOS de grau moderado e alteração da latência da onda V (p=0,01). Conclusão: A presença da AOS está associada à presença de alteração na condução nervosa do estímulo acústico na via auditiva em tronco encefálico. A presença de AOS de grau grave prejudicou a função coclear. De maneira geral, a função de transferência acústica da orelha média é similar entre os adultos com e sem AOS / Introduction: The obstructive sleep apnea (OSA) can change the normal sleep architecture, fragmenting it chronically with intermittent hypoxias and, to the long time, inducing to serious consequences to health. It is believed that the occurrence of respiratory events during sleep with the presence of apnea and hipopneia can damage the transduction mechanism of the inner ear and nerve impulses transmission along the auditory pathways, which are highly dependent on the oxygen supply. However, this association is not well established. Moreover, the acoustic transference function of middle ear could show alterations, due to the pressure changes that occur in upper airway during the sleep, typical of OSA pathophysiology. Objective: To compare the findings of the hearing evaluations between subjects with OSA and without OSA. Method: A total of 38 subjects of the male sex, mean age 35.8 (±7.2), were divided into four groups, which were matched for age and body mass index. The groups were classified by the means of polissomnography in without OSA (n=10), mild OSA (n=11), moderate OSA (n=8) and severe OSA (n=9). All the subjects denied a history of risk for hearing loss. These subjects were submitted to: conventional audiometry, tympanometry, ipsilateral, contralateral acoustic reflex, wideband acoustic immittance for measurements of energy of absorbance (EA) with click stimulus of 226 to 8000 Hz, distortion product of otoacoustic emissions (DPOAE) and click evoked auditory brainstem responses (ABR). The recorded data of each analysis were conducted to an appropriate statistical test and was adopted the significant level of 5% for all the tests. Results: The EA data did not showed statistical differences among the groups when considering only the OSA severity factor (without, mild, moderate or severe). For the interaction between OSA severity and frequency factors, the mean value of EA of moderate OSA group was significant higher than the mild OSA group (p=0.003) in 8000 Hz. The severe OSA group presented lower mean values of amplitudes of DPOAE when compared to the control group, mild and moderate OSA groups (respectively, p=0.02, p=0.03 and p=0.01). For ABR, no differences was observed in latencies waves I, III and V, and interpeaks I-III, III-V and I-V values among the groups. Conclusion: The presence of OSA is associated with the presence of alterations in the nerve conduction of acoustic stimuli in the auditory pathway in the brainstem. The presence of severe OSA impaired the DPOAE responses. In general, the acoustic transference function of middle ear is similar between the adults with and without OSA

Cette étude s’inscrit dans les efforts faits par l’industrie aéronautique pour la protection environnementale.Pour cela, un des objectifs principaux est de réduire les émissions de polluants et les émissions sonores des aéronefs. Les émissions polluantes sont liées à la qualité de la combustion qui dépend elle même de la conception des chambres de combustion. Les émissions sonores sont réduites grâce à des traitements passifs comme les structures absorbantes placées en paroi des moteurs pour diminuer le bruit de soufflante. Pour ces deux applications différentes, on utilise des matériaux perforés. En effet, les matériaux absorbants sont constitués d’une structure en nid d’abeilles surmontée d’une plaque perforée. Dans les chambres de combustion, les perforations permettent l’injection d’un air froid protégeant les parois des hautes températures, mais leur présence peut modifier la caractérisation acoustique de la chambre. L’objectif de cette thèse est de modéliser la réponse acoustique d’un matériau perforé. La taille des perforations étant petite devant les longueurs d’ondes sonores, des techniques de modélisation asymptotique adaptées à la résolution de problèmes multi-échelle peuvent être mises en œuvre. En effet, ces méthodes permettent de faire le lien entre les effets présents à l’intérieur d’une perforation et la réponse acoustique homogénéisée de la plaque perforée. Dans ces travaux,ce sont les effets visqueux présents dans les perforations qui ont été essentiellement étudiés. Ensuite,des simulations numériques directes ont été réalisées pour vérifier la validité des hypothèses émises lors de la modélisation asymptotique. Ces travaux de thèse ont permis d’améliorer la compréhension de la modélisation de la réponse acoustique des matériaux perforés. De plus, la méthode analytique présentée peut être mise en œuvre pour des perforations de géométrie complexe. / This study is part of the effort made by the aeronautic industry to protect the environment. Thus,one of the main objectives is to reduce aircraft polluting emissions and sound emissions. The pollutinge missions are linked to the combustion quality which depends on the combustion chamber’s design.Noise pollution is reduced thanks to passive treatments such as absorbing structures placed on engine walls. For both applications, perforated plates are used. Indeed, absorbing materials are composed of honey comb structures topped by a perforated plate. In combustion chambers, cold air is injected through perforations to protect the walls from high temperatures, but the perforations can modify the chamber’s acoustic behavior. The objective of this thesis is to model the acoustic response of aperforated material. The perforation size is smaller than the sound wave length, therefore asymptotic modeling techniques adapted to resolving multiscale problems can be implemented. Indeed, thesemethods allow to link the effects inside the perforation with the homogenized acoustic response of theperforated plate. In this study, the viscous effects inside the perforation have been analysed. Moreover,direct numerical simulations have been performed to verify the asymptotic modeling hypotheses. The findings of this thesis allow to understand the acoustic modeling of perforated materials. Furthermore,the developed analytical method can be implemented for perforations with complex shape.

La réduction des nuisances sonores est un enjeu permanent pour les acteurs de l’aéronautique. L’optimisation de la réduction de bruit apportée par les traitements acoustiques tapissant la nacelle des réacteurs turbofan passe par une caractérisation précise des matériaux employés dans l’environnement aéroacoustique d’utilisation, qui met en jeu un écoulement rasant de vitesse importante combiné à de forts niveaux sonores. L’objectif de cette thèse est de développer une méthode inverse pour la détermination de l’impédance acoustique de liners soumis à un écoulement rasant, basée sur des mesures non intrusives du champ de vitesse acoustique au-dessus du matériau par Vélocimétrie Laser Doppler (LDV). L’impédance de liner est obtenue par minimisation de l’écart entre le champ de vitesse acoustique mesuré et le champ simulé numériquement en résolvant les équations d’Euler linéarisées bidimensionnelles harmoniques, discrétisées par un schéma Galerkin discontinu. Le gradient de la fonction objectif minimisée est calculé via la résolution, à chaque itération, des équations directes et adjointes. Une première étape de validation du solveur est effectuée sur des cas-tests académiques, puis sur des cas expérimentaux impliquant des mesures de pression acoustique en paroi rigide opposée au liner. Dans un second temps, la méthode est appliquée à des mesures de vitesse acoustique obtenues par LDV dans le banc B2A de l’ONERA en l’absence d’écoulement. La dernière étape consiste à prendre en compte l’effet d’un écoulement rasant de profil cisaillé. Les impédances identifiées à partir de mesures LDV en présence d’écoulement ont notamment permis de gagner en compréhension sur les phénomènes d’absorption intervenant dans le banc B2A. / While aircraft noise constraints become increasingly stringent, efficient duct treatment of turbofan engines requires an accurate knowledge of liner impedance with grazing flow at high acoustic levels. This thesis aims at developing an impedance eduction method in the presence of grazing flow. The inverse process is based on acoustic velocity fields acquired by Laser Doppler Velocimetry (LDV) above the liner. The liner acoustic impedance is obtained by minimization of the distance between the measured acoustic velocity field and the simulated one. Computations rely on the resolution of the 2D linearized Euler equations in the harmonic domain, spatially discretized by a discontinuous Galerkin scheme. The gradient of the objective function is achieved by the resolution, at each iteration on the liner impedance, of the direct and adjoint equations. The solver is first validated on academic test cases, then on experimental results of acoustic pressure measurements at the rigid wall opposite the liner. Secondly the method is applied to acoustic velocity measurements obtained by LDV above the liner without flow, in the ONERA B2A test bench. The last step consists in taking into account the effects of a sheared grazing flow. The impedances educed from LDV measurements in the presence of flow namely allowed to gain insight into the absorption phenomena occuring in the B2A test bench.

A avaliação da integridade do sistema tímpano-ossicular é um pré-requisito para que o processo de diagnóstico audiológico infantil possa ser concluído com precisão, assim, muito têm se discutido em relação aos procedimentos utilizados na prática clínica para definir a presença ou ausência de problema condutivo. Nesse sentido, as medidas de imitância acústica de banda larga mostram-se como uma opção para o avanço na área. Diante disso, surgiu o interesse em ampliar os conhecimentos e trazer as características das medidas de imitância acústica de banda larga nas diferentes condições de orelha média. O objetivo do estudo foi caracterizar as medidas de imitância acústica de banda larga com os estímulos tom puro e chirp em crianças com perda auditiva sensorial de grau severo e profundo e diferentes padrões timpanométricos. Foram avaliadas 187 orelhas de 98 crianças na faixa etária de seis a 60 meses de idade, subdivididas em grupos de acordo com a pressão e compliância obtidas na timpanometria com sonda de 226 Hz. As medidas de imitância acústica de banda larga foram realizadas por meio do sistema de medidas do Acoustics\' Middle-Ear Power Analyzer - MEPA, versão 5.0, utilizando os estímulos tom puro e chirp, com faixa de frequência de 211 a 6000 Hz. Os valores de compliância e pressão obtidos na timpanometria convencional foram correlacionados às medidas de imitância acústica de banda larga, adotando-se testes estatísticos apropriados, com nível de significância de 0,05. Os resultados obtidos evidenciaram o efeito das faixas de frequência (grave, média e aguda) em todas as medidas analisadas, com exceção do delay da reflectância. Foi constatada influência de pressões correspondentes a -100 daPa ou mais negativas e também para pressões positivas acima de 25 daPa, e compliâncias menores que 0,2 ml nas medidas de imitância acústica de banda larga. Além disso, houve diferença significante entre os estímulos tom puro e chirp para frequências baixas para a absorvância e magnitude da impedância, com maior reflexo da variação dos valores de compliância e pressão nos resultados obtidos com estímulo chirp. Conclui-se que as características das medidas de imitância acústica de banda larga estão relacionadas à condição de orelha média e a frequência do estímulo teste. Para o delay da reflectância observou-se uma ampla variabilidade entre frequências ao analisar os grupos subdivididos pela pressão e também na frequência de 258 Hz ao analisar os grupos subdivididos pela compliância. / The evaluation of the integrity of the tympanic-ossicular system is a prerequisite for the child audiology diagnostic process to be completed accurately, thus, much has been discussed in relation to the procedures used in clinical practice to define the presence or absence of conductive problems. Hence, the wideband acoustic immittance measurements show to be an option to the advance in the field. As a result, the interest in expanding the knowledge and bringing the characteristics of wideband acoustic immittance measurements in the different conditions of middle ear, emerged. This study aimed at characterizing the wideband acoustic immittance measurements using pure and chirp stimuli in children presented with severe and profound sensorineural hearing loss and different tympanometric standards. 187 ears of 98 children in the age range six-sixty months, subdivided into groups according to pressure and compliance achieved through tympanometry with a 226 Hz probe, were assessed. Wideband acoustic immittance measurements were performed by the measuring system of the Acoustics\' Middle-Ear Power Analyzer - MEPA, version 5.0, using pure and chirp tone stimuli, in a frequency ranging from 211 to 6000 Hz. The values of compliance and pressure obtained through conventional tympanometry were correlated with wideband acoustic immittance measures, by applying suitable statistical tests, with a 0.05 significance level. The results achieved evidenced the effect of frequency bands (low, medium and high) in all measures examined, with the exception of the reflectance delay. The Influence of pressures -100 daPa or more negative ones and also in positive pressures above 25 Pa, and compliance lower than 0.2 ml in the wideband acoustic immittance measurements, was verified. In addition, there was a significant difference between pure tone and chirp stimuli at low frequencies for impedance absorbance and magnitude, with a greater reflex of the variation of compliance and pressure values in the results obtained with the chirp stimulus. It is concluded that the characteristics of broadband acoustic immittance measures are related to the condition of middle ear condition and the frequency of the test stimulus. For Reflectance delay, a wide variability between frequencies was observed when analyzing the groups subdivided by pressure and also in the frequency of 258 Hz, when analyzing the groups subdivided by compliance.

Dans le cadre de recherches menées par l'ANDRA, qui visent à évaluer la faisabilité de créer un stockage de déchets radioactifs dans la formation argileuse du Callovo Oxfordien, cette thèse s'intéresse à deux étapes indispensables pour obtenir une image 3D du sous sol. La première étape concerne la cartographie de la géométrie de la formation. Celle-ci est déterminée à partir de temps pointés le long de profils sismiques, orientés suivant deux directions principales. Aux intersections, les valeurs enregistrées par deux profils sont différentes. Le faible nombre d'intersections ne permettant pas une étude détaillée du comportement spatial de ces différences, elles sont analysées par le biais du pseudo variogramme croisé. L'analyse variographique permet de choisir un modèle cohérent pour l'ensemble des profils. À partir de ce modèle une estimation du temps corrigée est présentée. La deuxième étape concerne l'étude de l'impédance, variable liée aux propriétés intrinsèques de la roche. Deux types de mesure sont disponibles. D'une part l'impédance sismique résultant de l'inversion géophysique de l'amplitude enregistrée le long de profils de sismique réflexion est largement étendue dans la zone d'intérêt. D'autre part, l'impédance log, résultant du produit de la densité de la roche et de la vitesse des ondes P, n'est connue uniquement dans quelques puits. Le comportement spatial bivariable, le long de la direction verticale, a permis de formuler l'hypothèse suivante : chaque mesure d'impédance est décomposée en une somme d'une variable Z (commune aux deux mesures) et d'un résidu différent pour chaque mesure. Sous certaines hypothèses supplémentaires, il est possible d'estimer la composante commune sur l'ensemble des sections sismiques. En complément à ces études, d'autres points ont été évoqués, par exemple la correspondance entre procédés géophysiques et géostatistiques, ou la prise en compte d'incertitude sur les amplitudes. / In the framework of researches carried out by ANDRA (the French agency for nuclear waste), which aim at evaluating the feasibility of creating a repository of radioactive waste in the Callovo Oxfordian clay formation. This thesis studies two key steps to obtain a 3D image of the formation: its geometry and its internal heterogeneity. The geometry of the sedimentary formation is determined from seismic time picking along profiles. These profiles are oriented along two main directions. At the intersections, the values registered by two profiles are different. The low number of intersections does not allow a precise study of the spatial behavior of these differences; they are analyzed via the pseudo-cross-variogram. The variography analysis allows the choice of a coherent model for all the profiles, from which an estimation of the corrected time is presented. The internal heterogeneity is performed through the study of the impedance, a variable linked to the intrinsic properties of the rock. Two types of measurements are available. On one hand, the seismic impedance resulting from the geophysical inversion of the amplitude recorded along seismic reflection profiles is densely distributed in the area of interest. On the other hand, the impedance log, resulting from the product of rock density and P wave velocity, is known at only few wells. Bivariate spatial behavior along the vertical direction has allowed the formulation of the following hypothesis: each impedance measurement can be decomposed into a sum of a variable Z (common to both measures) and a residual specific to each measure. Under certain supplementary hypotheses, it is possible to estimate the common component along the seismic sections. Some complements to these studies are mentioned, for example the correspondence between geophysical and geostatistical methods or the consideration of uncertainty in the amplitudes.

La prédiction de la réduction passive du bruit nécessite l’utilisation de modèles d’impédance acoustique fiables. La proposition de tels modèles en présence d’écoulement est un problème qui reste ouvert. Les travaux réalisés dans cette thèse sont consacrés à la mise en place d’une méthode expérimentale et numérique permettant de tester la validité de modèles d’impédance acoustique de traitements SDOF en présence d’écoulement. Cette approche repose sur la comparaison de résultats expérimentaux issus d’un banc aéroacoustique, et de résultats numériques issus d’un modèle FEM-PML axisymétrique basé sur l’équation de Galbrun. Ainsi, dans la première partie de cette thèse, le modèle FEM-PML utilisé est présenté. Dans la seconde partie, des modèles d’impédance acoustique de SDOF tenant compte de l’écoulement sont exposés, ainsi que la méthode de validation de ces modèles et les résultats de ces validations. / Prediction of noise reduction requires reliable acoustic impedance models. The proposal of such models in the presence of a mean flow is a problem which remains open. This thesis is devoted to the development of an experimental and a numerical method to test the validity of SDOF treatments acoustic impedance models in the presence of mean flow. This approach is based on the comparison of experimental results from an aeroacoustical duct, and numerical results from a FEM-PML axisymmetric model based on Galbrun’s equation. Thus, in the first part of this thesis, the FEM-PML model is presented. In the second part, some acoustic impedance models are exposed, and the validation method and the results of these validations are presented.