Acoustic pressure in environment protection programs of developed countries is the one of most important issue after air and water pollution. Acoustic pressure is all around us, such like machines, traffics and some other things. It is not possible to completely stop the noise, but there are some certain ways were used to reduce it up to acceptable limits. The aim of this work is to measure the acoustic noise and find solution to reduce it. The first measurements were done indoor (workplace studio) focused on room acoustic. We measured the acoustic pressure for three heights in different places,but finally the most important results were selected and compared with respect to each others. The next measurements were performed outdoor to collect the results about spread of the noise, which were analyzed with certain limits. The main goal was to find how to safe the human health and maintain peaceful and healthy environmental.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The acoustic inadequacy in an environment for teaching and study of music can trigger problems in the process of learning music, because the music content or the speech itself, can be modified, creating possibilities of erroneous adaptations to inadequate conditions. Because of this, there is concern with the implementation of Law nº. 11 769/2008 that amends Law no. 9.394/1996 - Law of Guidelines and Bases of Education (LDB), which inserts the teaching of music in primary education on a mandatory way, but not exclusive in the school curriculum. This study aims to contribute to the integration of music in schools so that it can be done correctly, providing to the public school the opportunity to experience this learning. Therefore, it aims to propose recommendations for the adaptation of the existing rooms events, lectures and musical activities in the schools of the state. It was used as a sample, five different types of rooms existing in the state of basic education in Santa Maria - RS which are characterized by architectural forms and construction set in the '70s, '80s and '90s. We collected information on dimensions, geometry and materials, having as goal, to evaluate the acoustics of the rooms. We evaluated the acoustic characteristics of the room, with and without furniture, using measures to determine the impulse response of the acoustic parameters (ISO 3382/2009), of verify the acoustic quality (clarity of musical sounds) and the speech intelligibility. These acoustic parameters are the Reverberation Time, Decay Time Initial, Clarity, Definition and Speech Transmission Index. The evaluation results showed the reverberation times and acoustic parameters of the rooms to be unsuitable for music. There was a determination, through trials in reverberation room (ISO 354/2003),of the sound absorption of classes, chairs, backpacks and other common objects in classrooms. This a showed that the furniture has great influence on the behavior of absorption of the room, changing the experimental results when performed with the furnished room. But does not mean to be a solution to the acoustics conditions of the rooms studied, but rather a guide to possible modifications of the rooms, materials and furnishings. Thus, recommendations were proposed to the adaptation of the rooms now used for events, lectures and musical activities in the schools of the state, fulfilling the proposed objective. / A inadequação acústica em um ambiente destinado ao ensino e estudo da música pode desencadear problemas no processo de aprendizagem, pois os conteúdos musicais ou a própria fala, podem ser modificados, criando possibilidades de adaptações errôneas às condições existentes. Por isso a preocupação com a implementação da Lei nº. 11.769/ 2008, que altera a Lei nº. 9.394/1996 - Lei de Diretrizes e Bases da Educação (LDB), que insere o ensino de música na educação básica de forma obrigatória, mas não exclusiva nos currículos escolares. Este estudo pretende contribuir para que a inserção da música nas escolas seja feita de forma correta, propiciando ao público escolar a oportunidade de vivenciar esse aprendizado. Para isto, objetiva propor recomendações para a adaptação das salas já existentes e utilizadas para eventos, palestras e atividades musicais nas escolas da rede estadual. Foram utilizadas como amostra, as cinco diferentes tipologias de salas já existentes na rede estadual de educação básica de Santa Maria RS que se caracterizam por formas arquitetônicas e construtivas definidas nas décadas de 70, 80 e 90. Foram coletadas informações sobre dimensões, geometria e materiais, objetivando avaliar as condições acústicas das salas. Avaliaram-se as características acústicas das salas, com e sem mobília, utilizando-se medidas da resposta impulso para determinação de parâmetros acústicos (ISO 3382/2009), para verificar a qualidade acústica (clareza dos sons musicais) e a inteligibilidade da fala. Esses parâmetros acústicos são o Tempo de Reverberação, Tempo de Decaimento Inicial, Clareza, Definição e Índice de Transmissão da Fala. Os resultados da avaliação mostraram tempos de reverberação e parâmetros acústicos das salas inadequados para a música. Houve a determinação, através de ensaios em câmara reverberante (ISO 354/ 2003), da absorção sonora de classes, cadeiras, mochilas e outros objetos comuns em salas de aula. Também mostraram que o mobiliário tem grande influência no comportamento da absorção da sala, alterando os resultados experimentais quando realizados com a sala mobiliada. Porém não significa ser uma solução para as condições acústicas das salas estudadas, mas sim uma orientação para possíveis modificações das salas, seus materiais e mobília. Sendo assim, foram propostas recomendações para a adaptação das salas já utilizadas para eventos, palestras e atividades musicais nas escolas da rede estadual, cumprindo com o objetivo proposto.

Le besoin permanent de réduire le bruit des moteurs d’avion constitue un véritable engouement pour le développement de nouveaux traitements acoustiques. Les traitements traditionnels de type résonateur continuent d’être utilisé et permettent d’atténuer le son sur une bande de fréquence restreinte malgré l’augmentation du nombre de degré de liberté. Une alternative possible est l’utilisation de matériaux poreux, dit à réaction non localisée, qui permettent d’élargir le spectre d’atténuation. Ce rapport est consacré à la modélisation d’un traitement acoustique basé sur des matériaux poreux dans les conditions d’une manche d’entrée d’air de turboréacteur. Un modèle semi-analytique a donc été développé pour le calcul de la perte par transmission d’un conduit cylindrique traité en paroi et soumis à un écoulement uniforme. Une étude paramétrique a ensuite été réalisée afin de cibler les caractéristiques du traitement optimal pour une configuration aéronautique donnée. Des résultats expérimentaux sur une veine à échelle réduite sont également montrés et témoignent d’un certain accord avec le calcul. Enfin, dans le but d’approfondir les connaissances théoriques sur le problème, une étude préliminaire sur les effets d’une couche limite est réalisée et montre que sa prise en compte parait indispensable pour bien choisir les traitements acoustiques, surtout à haute fréquence. / The constant need to reduce noise emissions from aircraft engine leads to a real demand for developing new acoustic treatments. Conventional liners based on resonatorlike structure continue to be used and provide narrow-band attenuation in spite of an increasing degree of freedom. A possible alternative is the use of porous materials (nonlocally reacting), which offer the possibility of broadening the attenuation spectrum. This report deals with the modelling of an acoustic treatment based on porous materials for aeroengine nacelle inlet. A semi-analytical model is developed for predicting the transmission loss of a treated cylindrical duct containing uniform mean flow. Then, a parametrical study is carried out in order to target the optimal liner characteristics for a given turbofan duct application. Also, experiments have been performed on a small-scale duct and have shown agreement with the simulation. Finally, for a better theoretical unv derstanding of the problem, a preliminary study on the effect of a boundary layer is conducted and shows that its consideration seems to be essential for optimal choice of acoustic lining, espacially at high frequencies.

O objetivo deste trabalho é estudar o fenômeno da força de radiação acústica produzida por ondas progressivas e estacionárias. Neste trabalho o estudo da força produzida por ondas estacionárias é aplicado na análise de um levitador acústico e o estudo da força de radiação acústica por ondas progressivas é feito visando a futura construção de um separador acústico. Neste trabalho é utilizado o método dos elementos finitos para simular o comportamento de um levitador acústico. Primeiramente, é feita a simulação de um levitador acústico que consiste de um transdutor de Langevin com uma face de emissão plana que opera na freqüência de aproximadamente 20 kHz e um refletor plano. O método dos elementos finitos é utilizado para determinar o deslocamento da face do transdutor e o potencial acústico que atua numa esfera pequena. O deslocamento da face do transdutor obtido numericamente é comparado com o medido experimentalmente por um vibrômetro de fibra ótica e o potencial acústico determinado pelo método dos elementos é verificado experimentalmente colocando pequenas esferas de isopor no levitador. Depois de verificar o modelo numérico, o método dos elementos finitos é utilizado na otimização de um levitador acústico composto de um refletor côncavo e um transdutor com face de emissão côncava. Os resultados numéricos mostram que a força de radiação acústica no novo levitador é aumentada em 604 vezes quando comparada com o levitador composto de um transdutor com face plana e refletor plano. Este trabalho também apresenta um modelo numérico para determinar a trajetória de partículas esféricas na presença de uma onda de ultra-som progressiva. O modelo assume que as seguintes forças atuam na partícula: gravidade, empuxo, forças viscosas e força de radiação acústica devido a uma onda progressiva. Com o objetivo de não restringir o tamanho das partículas que podem ser utilizadas no modelo é empregada uma equação empírica do coeficiente de arrasto, válida para uma grande faixa de número de Reynolds. O modelo proposto requer a distribuição de pressão gerada pelo transdutor de ultra-som. A distribuição de pressão é medida experimentalmente utilizando um hidrofone calibrado. A verificação do modelo é feita soltando-se pequenas esferas de vidro (com diâmetros da ordem de 500 m) em frente a um transdutor de ultra-som de 1 MHz e 35 mm de diâmetro. / The objective of this work is to study the acoustic radiation force produced by progressive and standing waves. In this work, the studies related to the acoustic radiation force generated by ultrasonic standing waves are applied in the analysis of an acoustic levitator and the studies involving the acoustic radiation force generated by progressive waves are conducted aiming the design of acoustic separators. In this work, the finite element method is used to simulate an acoustic levitator. First, an acoustic levitator consisting of a 20 kHz Langevin ultrasonic transducer with a plane radiating surface and a plane reflector is simulated by the finite element method. The finite element method is used to determine the transducer face displacement and the acoustic radiation potential that acts on a small sphere. The numerical displacement is compared with that obtained by a fiber-optic vibration sensor and the acoustic radiation potential determined by the finite element method is verified experimentally by placing small Styrofoam spheres in the levitator. After verifying the numerical method, the finite element method was used to optimize an acoustic levitator consisting of a concave-faced transducer and a curved reflector. The numerical results show that the acoustic radiation force in the new levitator is enhanced 604 times compared with the levitator consisting of a plane transducer and a plane reflector. This work also presents a numerical model to determine the trajectory of sphere particles when submitted to ultrasonic progressive waves. This model assumes that the following forces act on the particle: gravity, buoyancy, viscous forces and acoustic radiation force due to the progressive wave. In order not to restrict the model to a small particle size range, the viscous forces that act on the sphere are modeled by an empirical relationship of drag coefficient that is valid for a wide range of Reynolds numbers. The numerical model requires the pressure field radiated by the ultrasonic transducer. The pressure field is obtained experimentally by using a calibrated needle hydrophone. The numerical model validation is done by dropping small glass spheres (on the order of 500 m diameter) in front of a 1-MHz 35-mm diameter ultrasonic transducer.

Orientador: Stelamaris Rolla Bertoli / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-16T13:37:38Z (GMT). No. of bitstreams: 1 Oiticica_MariaLuciaGondimdaRosa_D.pdf: 8031849 bytes, checksum: 7b186c29405cc5443f860aedc6138082 (MD5) Previous issue date: 2010 / Abstract: Com a crise energética na década de 60, varias discussões foram levantadas com o propósito de estimular as edificações a estarem inseridas em um contexto sustentável. As edificações, por serem grandes consumidoras dos recursos naturais, buscam ser mais eficientes energeticamente que outras quando estas proporcionam as mesmas condições ambientais com menor consumo energético. Para tal, a bioclimatologia que relaciona o estudo do clima aplicado à arquitetura, quando focada nas decisões arquitetônicas, torna-se uma excelente ferramenta para se obter valores de consumo energéticos mais baixos. Nas regiões de clima quente úmido, a utilização do peitoril ventilado como estratégia de projeto bioclimático, é uma ferramenta de projeto muito bem aplicada dentro deste conceito. O peitoril ventilado é um dispositivo geralmente executado em concreto, em formato geralmente em "L" invertido, sobreposto a uma abertura localizada no peitoril abaixo das janelas, que tem por finalidade atuar como fonte complementar do movimento de ar proporcionado pelas aberturas. A presença deste elemento nas aberturas das edificações pode proporcionar uma redução do consumo de energia, uma vez que estimula a climatização natural, mas ao mesmo tempo permite a passagem de ruído para o interior das edificações. Este trabalho tem o objetivo de investigar o desempenho acústico de diversos protótipos de peitoril ventilado, utilizados em fachadas como estratégia passiva de projeto bioclimático. Como método de avaliação acústica foi medido o grau de isolamento acústico dos peitoris ventilados através da diferença de nível sonoro padronizado mantendo-se fixa a área de abertura e variando as características construtivas do elemento de fachada investigado. Diante dos diversos materiais construtivos utilizados nos protótipos foi possível verificar significativas alterações na atenuação acústica dos diferentes modelos investigados. Com isto, registra-se que a utilização de uma estratégia passiva de projeto bem aplicada poderá propiciar em melhora nas condições acústica no interior das edificações, estimulando assim a utilização da climatização natural e consequentemente contribuindo para um menor consumo energético. / Abstract: With the energy crisis in the 60s, several discussions have been raised with the intention of stimulating the buildings to be included in a sustainable context. The buildings, being large consumers of natural resources, seek to be more energy efficient than others when they provide the same environmental conditions with lower energy consumption. To this end, the bioclimatology that connects the study of climate applied to architecture, when focused on architectural decisions, it is an excellent tool to obtain values of lower energy consumption. In regions of warm humid climate, the use of ventilated window sill as bioclimatic design strategy is a very well implemented project tool in this concept. The ventilated window sill is a device generally in "L" inverted, made on concrete, overlaid with a sill opening located below the window, mainly act as a supplementary movement of air source provided by openings. The presence of this element in the openings of buildings can provide a reduction in energy consumption since it stimulates the natural climatization, but at the same time allows the passage of noise to the interior of buildings. This work aims to investigate the sound insulation of a wall containing different prototypes of ventilated windows sill commonly used in walls as a passive bioclimatic design. The presence of this element in the openings of buildings can provide a reduction in energy consumption since it stimulates the natural air conditioning, but at the same time allows the passage of noise to the interior of buildings. This work aims to investigate the sound insulation of a wall containing different prototypes of ventilated windows sill commonly used in walls as a passive bioclimatic design. As methodology, different settings of ventilated window sill were inserted in façade of flat opening building but made of different materials. The sound insulation performance of each element used in a façade were compared and analyzed. In preliminary results it was possible to verify changes in acoustic attenuation of different types of ventilated windows sill investigated. That is, records that the use of a passive strategy and implemented the project could offer in improving thermal and acoustic conditions inside the buildings with lower energy consumption. / Doutorado / Arquitetura e Construção / Doutor em Engenharia Civil

Orientador: Jose Maria Campos dos Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-25T04:25:40Z (GMT). No. of bitstreams: 1 Colinas_NiltonGilber_M.pdf: 6668829 bytes, checksum: 0f5fe00364a351d5d5859c9c042c161c (MD5) Previous issue date: 1999 / Resumo: Neste trabalho procurou-se explorar a técnica de Holografia Acústica de Campo Próximo (Nearfield Acoustic Holography - NAB), que tem se mostrado como uma forma de análise para problemas vibroacústicos. A holografia é um processo que permite determinar as características de um campo de ondas acústicas usando a Transformada de Fourier Discreta (Discrete Fourier Transform - DFT), a partir de uma grade de pontos de medições regularmente espaçados obtidos em um ambiente acústico onde a função de Green é conhecida. O presente trabalho apresenta uma breve revisão dos princípios desta técnica com uma aplicação na reconstrução de propriedades vibroacústicas de estruturas. O campo de pressão, campo de velocidade das partículas e intensidade acústica gerados por um elemento estrutural vibrante foram as grandezas reconstruídas através da técnica NAH em diferentes posições do espaço. A fim de minimizar os problemas de leakage oriundos do processamento dos sinais, a Série de Fourier Discreta Regressiva (Regressive Discrete Fourier Series - RDFS) foi utilizada como alternativa às técnicas de janelamento do sinal. Resultados obtidos para uma estrutura do tipo placa são analisados, validados e comparados com previsões teóricas / Abstract: In this work, the Nearfield Acoustic Holography technique - NAH was explored as an way to analyze vibroacoustic problems. Holography is a process that allows to determine acoustic fields characteristics using a Discrete Fourier Transform - DFT, from a regular grid of measurements obtained in an acoustic environment for which the Green' s function is known. This work presents a brief principle's review of this technique with an application on the reconstruction of the vibroacoustic properties of structures. The pressure field, particle velocity field and acoustical intensity generated by a vibrating structural element were reconstructed through the NAH technique in different spatial positions. ln order to minimize spatial leakage problems from signal processing a Regressive Discrete Fourier Series ¿ RDFS was utilized as an alternative to windowing techniques. Results obtained from a plate type structure were analyzed, validated and compared with theoretical predictions / Mestrado / Mecanica dos Solidos / Mestre em Engenharia Mecânica

Le but de la thèse est de modéliser la génération d’ondes élastiques ultrasonores émises par EMATs dans une pièce ferromagnétique, modélisation appliquée au domaine du contrôle non destructif (CND). Les traducteurs EMATs combinent deux physiques différentes : électromagnétisme et élastodynamique. L’enjeu est d’intégrer dans la plateforme de simulation CIVA, dédiée notamment aux CND par courant de Foucault et par ultrasons, les éléments de modélisation inhérents à la problématique multi-physique posée. Ces éléments sont multiples et concernent premièrement la modélisation des forces électromagnétiques créées par un EMAT : la force de Lorentz, existant dans tous milieux conducteurs, et les forces d’aimantation et de magnétostriction, spécifiques aux milieux ferromagnétiques. Deuxièmement, la modélisation proposée prend aussi en compte le phénomène de création d’harmoniques, phénomène dû aux différentes forces et traduisant le fait que les fréquences de l’onde ultrasonore émise peuvent être des harmoniques des fréquences du signal d’excitation de l’EMAT. Le modèle de forces et de création d’harmoniques permet de modéliser des situations de contrôle non prises en compte par les modèles de la littérature, notamment lorsque les champs statiques créés par l’EMAT sont faibles ou lorsque le courant d’excitation possède une forte intensité. Enfin, les forces électromagnétiques sont transformées en contraintes surfaciques équivalentes pour correspondre au formalisme des données d’entrée des modèles de rayonnement des ondes élastiques implémentés dans CIVA. L’outil informatique développé permet donc de traiter toute configuration et condition d’utilisation des EMATs, constituant un outil d’optimisation de leur conception. Les caractéristiques électromagnétiques de différents matériaux, données par l’expérience, sont utilisées pour mener diverses études paramétriques. / The present study aims at modelling the ultrasonic wave generation by EMATs into a ferromagnetic part in the context of non-destructive testing (NDT). Wave radiation by EMATs combines two different kinds of physical phenomena: electromagnetism and elastodynamics. The issue is to implement into the NDT simulation platform CIVA, dedicated in particular to eddy current and ultrasonic NDT, the models developed in the present work. These developments are of various nature and firstly concern the modelling of the electromagnetic forces created by an EMAT: the Lorentz force, existing in any conductive media, and the magnetization and the magnetostriction forces, which add up when the medium is further ferromagnetic. Secondly, the proposed models take into account the generation of harmonics due to the three forces. Ultrasonic frequencies of the generated ultrasonic waves can be harmonics of the frequencies of the excitation electrical signal. The model of force and harmonic generation allows us to deal with configurations not treated in the literature, namely, when the static field created by the EMAT is low or when the excitation current intensity is high. Finally, the three electromagnetic forces are transformed into equivalent surface stresses readily usable as entries of an existing model of ultrasonic wave radiation already implemented in CIVA. Thus, the combination of all these models and their translation as a numerical tool running within the CIVA platform can be used for optimizing the design of EMAT. Experimentally measured electromagnetic characteristics of different materials are used to perform various parametric studies.

No description available.

High levels of speech recognition have been obtained with cochlear implant users in quiet conditions. In noisy environments, speech recognition deteriorates considerably, especially in speech-like noise. The aim of this study was to determine what underlies measured speech recognition in cochlear implantees, and furthermore, what underlies perception of speech in noise. Vowel and consonant recognition was determined in ten normal-hearing listeners using acoustic simulations. An acoustic model was developed in order to process vowels and consonants in quiet and noisy conditions; multi-talker babble and speech-like noise were added to the speech segments for the noisy conditions. A total of seven conditions were simulated acoustically; namely for recognition in quiet and as a function of signal-to-noise ratio (0 dB, 20 dB and 40 dB speech-like noise and 0 dB, 20 dB and 40 dB multi-talker babble). An eight- channel SPEAK processor was modelled and used to process the speech segments. A number of biophysical interactions between simulated nerve fibres and the cochlear implant were simulated by including models of these interactions in the acoustic model. Biophysical characteristics that were modelled included dynamic range compression and current spread in the cochlea. Recognition scores deteriorated with increasing noise levels, as expected. Vowel recognition was better than consonant recognition in general. In quiet conditions, the features transmitted most efficiently for recognition of speech segments were duration and F2 for vowels and burst and affrication for consonants. In noisy conditions, listeners mainly depended on the duration of vowels for recognition and the burst of consonants. As the SNR decreased, the number of features used to recognise speech segments also became fewer. This suggests that the addition of noise reduces the number of acoustic features available for recognition. Efforts to improve the transmission of important speech features m cochlear implants should improve recognition of speech in noisy conditions. / Dissertation (MEng (Bio-Engineering))--University of Pretoria, 2008. / Electrical, Electronic and Computer Engineering / unrestricted

A simple method is described to record the radiated sound of musical instruments and to extrapolate the sound field to distances further away from the source. This is achieved by considering instruments as complex point sources. It is demonstrated that this simplification method yields plausible results not only for small instruments like the shakuhachi but also for larger instruments such as the double bass: The amplitude decays in a given manner and calculated interaural signal differences reaching the listener decrease with increasing distance to the source. The method can be applied to analyze the sound radiation characteristics as well as the radiated sound field in a listening region regardless of room acoustical influences. Implementations in terms of room acoustical simulations, spatial additive synthesis and sound field synthesis are discussed.