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Kuster, Martin. "Inverse methods in room acoustics with under-determined data and applications to virtual acoustics." Thesis, Queen's University Belfast, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486233.
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With the advent of commercial surround sound systems there is a growing demand for 11 system that can convert existing mono and stereo recor~ings into a surround sound recording. A part of this problem is to generate the reverberation for the additional audio channels from the reverberation in the mono or stereo recording. . , In thi~ thesis, it is investigated whether a room model can be constructed from one or two room impulse responses and in which a virtual surround sound recording can then be perfonned. The estimation of the room model parameters is based on the three well-mown room acoustic models; the geometrical acoustic model with specular reflections, the eigenmode model and the diffuse field model. It is shown that the scope with the geometrical acoustic and the eigenmode model is limited but it is possible to obtain useful and consistent results for the room volume and the source-to-receiver distance from the diffuse field model. Based on these findings, the problem of generating multiple room impulse responses from one or two input room impulse response(s) is approached slightly differently. The very early part of the room impulse responses (the early reflections) is generated by a geometrical model with specular and diffuse reflections. The remainder of the room impulse responses are copies of the input room impulses obtained by convolution with a set of filters that control the coherence between them. The values for the coherence are given by expressions for the coherence between microphones with first-order directivity in a diffuse field and these expressions are derived in the thesis. The results from objective and subjective tests indicate that this method works successfully.
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Carwile, Zachary Thomas. "Validation of a 3-D Virtual Acoustic Prototyping Method For Use In Structural Design." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/30988.
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Virtual acoustic prototyping (auralization) is the rendering of a virtual sound field that is created from the calculated acoustic response of a modeled structure. Auralization is useful in the design and subjective evaluation of buildings, automobiles, and aircraft. The virtual acoustic prototyping method in this thesis uses finite element modeling (FEM), the equivalent source method (ESM), and head-related transfer functions (HRTFs). A tradeoff exists between the accuracy of the auralization process and the number of equivalent sources (and thus computational power) that are required.
The goal of this research is to validate (numerically and subjectively) a virtual acoustic prototyping method for use in structural design; this thesis illustrates the first attempt to apply the aforementioned methods to a structure that represents a typical building or automobile. The structureâ s acoustics were modeled using FEM, ESM, and HRTFs. A prototype of the modeled structure was built. A 36% correlation was achieved between the model and prototype. Slight variations in boundary conditions caused significant FEM error, but the data represented a typical structure.
Psychoacoustic comparison testing was performed to determine the number of equivalent sources that must be used in an auralization to accurately recreate the sound field. The number was found to be dependent on the type of noise that is played to the test subject. A clear relationship between the numerical correlation of two sounds and the percentage of subjects who could hear a difference between those two sounds was established for impulsive, broadband, and engine noises.Master of Science
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Webb, Craig Jonathan. "Parallel computation techniques for virtual acoustics and physical modelling synthesis." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/15779.
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The numerical simulation of large-scale virtual acoustics and physical modelling synthesis is a computationally expensive process. Time stepping methods, such as finite difference time domain, can be used to simulate wave behaviour in models of three-dimensional room acoustics and virtual instruments. In the absence of any form of simplifying assumptions, and at high audio sample rates, this can lead to simulations that require many hours of computation on a standard Central Processing Unit (CPU). In recent years the video game industry has driven the development of Graphics Processing Units (GPUs) that are now capable of multi-teraflop performance using highly parallel architectures. Whilst these devices are primarily designed for graphics calculations, they can also be used for general purpose computing. This thesis explores the use of such hardware to accelerate simulations of three-dimensional acoustic wave propagation, and embedded systems that create physical models for the synthesis of sound. Test case simulations of virtual acoustics are used to compare the performance of workstation CPUs to that of Nvidia’s Tesla GPU hardware. Using representative multicore CPU benchmarks, such simulations can be accelerated in the order of 5X for single precision and 3X for double precision floating-point arithmetic. Optimisation strategies are examined for maximising GPU performance when using single devices, as well as for multiple device codes that can compute simulations using billions of grid points. This allows the simulation of room models of several thousand cubic metres at audio rates such as 44.1kHz, all within a useable time scale. The performance of alternative finite difference schemes is explored, as well as strategies for the efficient implementation of boundary conditions. Creating physical models of acoustic instruments requires embedded systems that often rely on sparse linear algebra operations. The performance efficiency of various sparse matrix storage formats is detailed in terms of the fundamental operations that are required to compute complex models, with an optimised storage system achieving substantial performance gains over more generalised formats. An integrated instrument model of the timpani drum is used to demonstrate the performance gains that are possible using the optimisation strategies developed through this thesis.
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Takeuchi, Takashi. "Systems for virtual acoustic imaging using the binaural principle." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249594.
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Amengual, Garí Sebastià Vicenç [Verfasser]. "Investigations on the Influence of Acoustics on Live Music Performance using Virtual Acoustic Methods / Sebastià Vicenç Amengual Garí." Detmold : Hochschule für Musik Detmold, Musikbibliothek, 2018. http://d-nb.info/1173637931/34.
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Hill, Peter A. "Front back confusion in systems for the production of virtual acoustic images." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245307.
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McDermott, Scott. "An Analysis of Accurate, Real-Time Reproduction of 3D Acoustics in Virtual Environments." Thesis, University of Louisiana at Lafayette, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3687696.
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Many of the applications, virtual environments, and video games available to average computer users integrate stunning three-dimensional (3D) graphics and real-world visualizations. Developers spend an extraordinary amount of time and effort creating these immersive, realistic virtual environments, primarily focusing on the graphics components. Within these virtual realities, the user should easily perceive the locations of sound sources accurately, as well as the acoustic nature of the environment. However, for reasons of economy and simplicity, most developers apply readily available industry standards for generating pseudo-3D sounds in their applications. This research explores the shortcomings of these standards, proposes an effective alternative, and provides a detailed analysis of the various possible approaches.
This project includes a number of computationally efficient, physics-based 3D acoustics simulations, each of which will produce realistic aural reproductions. The primary goal is to evaluate and compare these algorithms against each other, non-3D sound reproduction, and the current industry standards (e.g. Microsoft's DirectX® pseudo-3D algorithm). We will test three hypotheses. First, users will find that physics-based 3D algorithms will render improved auralization reproductions compared against industry standards like DirectX® and/or OpenAL. Second, localization and spatialization will improve with user training when using these algorithms. Finally, we should discover an unambiguous ranking system for the quality of each tested algorithm.
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Collins, Christopher Michael. "Development of a Virtual Acoustic Showroom for Simulating Listening Environments and Audio Speakers." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/9965.
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Virtual acoustic techniques can be used to create virtual listening environments for multiple purposes. Using multi-speaker reproduction, a physical environment can take on the acoustical appearance of another environment. Implementation of this environment auralization could change the way customers evaluate speakers in a retail store.
The objective of this research is to develop a virtual acoustic showroom using a multi- speaker system. The two main components to the virtual acoustic showroom are simulating living environments using the image source method, and simulating speaker responses using inverse filtering. The image source method is used to simulate realistic living environments by filtering the environment impulse response by frequency-dependant absorption coefficients of typical building materials. Psychoacoustic tests show that listeners can match virtual acoustic cues with appropriate virtual visual cues. Inverse filtering is used to "replace" the frequency response function of one speaker with another, allowing a single set of speakers to represent any number of other speakers. Psychoacoustic tests show that listeners could not distinguish the difference between the original speaker and the reference speaker that was mimicking the original. The two components of this system are shown to be accurate both empirically and psychologically.Master of Science
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Kahana, Yuvi. "Numerical modelling of the head-related transfer function." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326799.
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Lalime, Aimee L. "Development of a Computationally Efficient Binaural Simulation for the Analysis of Structural Acoustic Data." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/34524.
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Binaural simulation is the recreation of a three-dimensional audio environment around a listener's head. The binaural simulation of structural acoustic data would open new opportunities in virtual prototyping and simulation. By modeling the structure as an array of vibrating monopoles and applying Head Related Transfer Functions (HRTFs) to each of the sources, a binaural simulation of this type can be created. Unfortunately, this simulation method requires an extensive amount of computer power and speed for real-time simulation, more so than is available with current technology.
The objective of this research is to reduce the number of computations required in the binaural simulation of structural acoustic data. This thesis details two methods of reducing the number of real-time calculations required in this binaural analysis: singular value decomposition (SVD), and equivalent source reduction (ESR). The SVD method reduces the complexity of the HRTF computations by breaking the HRTFs into dominant singular values and vectors. The ESR method reduces the number of sources to be analyzed in real-time by replacing sources on the scale of a structural wavelength with sources on the scale of an acoustic wavelength. The ESR and SVD reduction methods can be combined to provide an estimated computation time reduction of 99.4%. In addition, preliminary tests show that there is a 97% correlation between the results of the combined reduction methods and the results found with current binaural simulation techniques.Master of Science
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Borß, Christian [Verfasser]. "An Improved Parametric Model for the Design of Virtual Acoustics and its Applications / Christian Borß." München : Verlag Dr. Hut, 2011. http://d-nb.info/1018982388/34.
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Völk, Florian [Verfasser]. "Interrelations of Virtual Acoustics and Hearing Research by the Example of Binaural Synthesis / Florian Völk." München : Verlag Dr. Hut, 2013. http://d-nb.info/104230758X/34.
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Zheng, Haosheng, and Kaichun Zhang. "Noise Analysis of Computer Chassis and Secondary Sound Source Noise Reduction." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-18547.
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This article focuses on computer noise analysis and noise reduction processing. With the popularity of computers, people are increasingly demanding the comfort of using computers. Solving the noise problem of the computer case can make the working environment more comfortable. People working in a noisy environment for a long time can cause anxiety and the quality of work is not high. The main purpose of this paper is to analyse the characteristics of computer noise and to reduce the noise of the chassis through the secondary sound source. Through the comparison of the experimental and simulation results, the noise reduction effect of the secondary sound source on the computer case is obtained. This paper can provide a scientific reference for the manufacture of computer chassis and improvement of noise.
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Thery, David. "Architectural auralizations : towards the integration of virtual acoustic design in architecture." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS016.
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Cette thèse a étudié l’usage des auralisations durant la phase de design de projets architecturaux. Cette technologie, qui consiste à rendre audibles des simulations numériques à partir de modèles acoustiques géométriques, a été beaucoup utilisée en recherche, allant d’études cognitives à l’évaluation de l’acoustique des salles de concert, en passant par des études archéoacoustiques permettant la conservation du patrimoine via la reconstitution de l’empreinte acoustique de lieux historiques. La question ici était donc d’évaluer la potentielle amélioration que l’usage des auralisa- tions apporterait durant la conception d’espaces architecturaux. En se basant sur la théorie de l’acceptabilité pratique, l’usage des auralisations a été étudié à partir de questionnaire et entretiens de consultants en acoustique, ainsi que l’observation d’un cas pratique d’utilisation, en collaboration avec Theatre Projects Consultants. Ces études ont permis l’identification des principaux usages des auralisations, ainsi que les difficultés rencontrées, tant déclarées qu’observées, freinant l’adoption par les consul- tants. L’une des nécessités pour favoriser cette adoption tient dans la fiabilité de la technologie, que ce soit les outils eux-mêmes, ou les rendus de ces auralisations. La stabilité de la perception auditive a donc été évaluée, comparant différents systèmes de restitution. La méthode de reproduction sonore pour commencer, en comparant un rendu Binaural traqué et un rendu Ambisonic. De même, l’influence du système de VR visuel pour des auralisations multimodales a été évalué. Une relative stabilité de notre perception auditive a été observée, avec toutefois un léger impact du système sur l’évaluation de l’impression d’enveloppement (LEV) et de la largeur apparent de source (ASW). Des efforts sur l’adaptabilité des outils d’auralisations, et le transfert de connaissances de la recherche á l’industrie sont nécessaires pour permettre de mieux intégrer les auralisations dans les pratiques des architectes et acousticiensThis thesis investigated the use of auralization in the design phase of architectural projects. While this technology, which consists of rendering audible numerical acoustical simulations, has been extensively used in research, from cognitive to human-computer interfaces to archeology to concert halls acoustics evaluation studies, only limited data existed on its use by acoustical consultants for acoustical design. The question was to evaluate if auralizations can improve the processes of acoustical design for the conception of architectural spaces. Based on the practical acceptability theory, the use of auralizations has been studied through questionnaire and interviews of acoustical consultants, as well as the observation of a practical case study project, conducted in collaboration with Theatre Projects Consultants. These enabled the identification of the main uses of auralizations, as well as the difficulties encountered that impede the adoption of the technology. One of the requirements for its adoption is the accuracy and reliability of both the results and the tools themselves. Therefore, the stability of auditory perception was assessed in perceptive studies along a set of subjective attributes, with auralizations rendered over different interfaces, including sound reproduction methods and VR visual interfaces. The two sound reproduction methods compared were head-tracked Binaural and Ambisonic while the VR visual devices compared were a HMD and a CAVE-light system. A relative stability of auditaptory perception was observed, while the perceived Envelopment and Apparent Source Width were slightly impacted by the rendering system in both cases. Efforts in the adaptability of auralization tools for use in architectural design and knowledge transfer from research to industry are still needed for a better integration of auralizations in architects and acousticians workflow
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Faria, Regis Rossi Alves. "Auralização em ambientes audiovisuais imersivos." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-29092013-105249/.
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Nos últimos anos os avanços em áudio multicanal e sistemas envolventes despertaram um grande interesse pelas técnicas para a auralização de campos sonoros espaciais, capazes de recriar ambientações acústicas com grande realismo, envolvendo o ouvinte completamente. Um estudo sobre as tecnologias e soluções para áudio espacial mostrou que a construção de auralizadores envolve quatro blocos funcionais fundamentais. Mas, embora existam muitas técnicas e ferramentas disponíveis, não há uma arquitetura integradora para produção de áudio espacial que permita ao desenvolvedor selecionar as técnicas que deseja e montar uma solução com um grau de refinamento arbitrário que atenda a seus requisitos. Apresenta-se uma arquitetura modular aberta em quatro camadas para produção de áudio espacial em ambientes audiovisuais imersivos. Como estudo de caso, aborda-se a implementação de um auralizador Ambisonics para a CAVERNA Digital. Verifica-se que a auralização pode fornecer a correta perspectiva acústica do ambiente virtual necessária para uma percepção mais realista do espaço, e que a abordagem aberta para se implementar sistemas de áudio 2D/3D apresenta vantagens. Os resultados da implementação são apresentados e discutidos. Como conclusões, identificam-se desafios na implementação e os trabalhos futuros.Recent advances in multichannel audio and surround systems have contributed to an increasing interest for spatial sound field auralization, capable of delivering acoustic ambience with great realism, and surrounding listener completely. A study on technologies and solutions for spatial sound has shown that building auralizators involve four major functional blocks, but, although there are many techniques and tools available, there is not an integration architecture for spatial audio production which permits developers to select their favorite techniques, and build a solution with an arbitrary refinement level, as wished. It is presented a four level modular open architecture for spatial audio production in immersive audiovisual environments. As a case study, an Ambisonics auralizator is implemented for the CAVERNA Digital CAVE. It is verified that auralization can deliver the correct acoustical perspective for the virtual environment necessary for a more realistic perception of space, and that an open approach presents advantages in 2D/3D audio systems design. Implementation results are presented and discussed. As conclusions, challenges and future works are presented.
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Demoucron, Matthias. "On the control of virtual violins - Physical modelling and control of bowed string instruments." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00349920.
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Cette thèse porte sur le contrôle de la synthèse sonore par modélisation physique des instruments à corde frottée. Elle se base, d'une part, sur l'exploration systématique de l'influence des paramètres de contrôle (pression d'archet, vitesse de l'archet et distance au chevalet) sur le comportement du modèle, et d'autre part, sur la mesure du contrôle effectif qu'exerce l'instrumentiste afin d'obtenir un contrôle réaliste du modèle physique. Un modèle physique basé sur la résolution modale de l'équation de la corde est d'abord présenté et implémenté pour la synthèse sonore du violon. Le comportement du modèle physique est ensuite examiné en effectuant des simulations et se concentre sur deux aspects: la ``jouabilité", c'est-à-dire l'espace des paramètres de contrôle dans lequel un mouvement de Helmholtz périodique est obtenu, et les variations des propriétés du son synthétisé (fréquence d'oscillation, niveau sonore et centroïde spectral) à l'intérieur de cet espace de paramètres. La deuxième partie de ce travail concerne la mise au point d'un capteur pour mesurer la force d'appui de l'archet sur la corde dans un contexte de jeu réel. Le capteur est ensuite combiné avec un système optique de capture du mouvement afin de mesurer l'ensemble complet des paramètres de jeu du violoniste. La dernière partie présente l'analyse des mesures de ces paramètres de contrôle pour des modes de jeu typiques (sautillé, spiccato, martelé, tremolo, détaché). Ces mesures permettent de décrire certaines propriétés du geste instrumental et de proposer un contrôle réaliste de la synthèse sonore pour différents modes de jeu et différentes tâches musicales.
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Naranjo, José Francisco Lúcio. "Aperfeiçoamentos no código computacional RAIOS incluindo aurilização." Universidade do Estado do Rio de Janeiro, 2010. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=1576.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorNeste trabalho se revisam os principais aperfeiçoamentos implementados no código computacional de simulação numérica de acústica de salas denominado RAIOS. Tais aperfeiçoamentos são divididos em quatro grupos: processo de importação de informação a partir de arquivos DXF; a implementação de novos parâmetros de qualidade acústica, assim como o cálculo do nível de pressão sonora; modificações para lidar com casos de acústica de exteriores (ruído urbano) e por último; inserção do módulo de realidade virtual acústica. Inicialmente, é apresentada uma breve revisão do estado anterior do código computacional RAIOS e, em seguida, os modelos que foram implementados no software. Os resultados obtidos foram precisos e os erros apresentados são justificados através da análise das características dos modelos e métodos adotados pelo simulador.
In this work, the most important improvements implemented in the computer code of numeric simulation of room acoustics, called RAIOS, are presented. These improvements are divided in four groups: Data importation process from DXF files; implementation of new acoustic quality parameters and steady state sound pressure level calculation; modifications in order to deal with cases of open field acoustics (urban noise); and implementation of the acoustic virtual reality module. Initially, a brief overview of the previous version of the computer code RAIOS is done. Then, the background theory of the procedures performed in the source code are presented. The results obtained were accurate and the encountered errors are justified through the characteristics analysis of the models and methods adopted by the simulator.
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Viala, Romain. "Towards a model-based decision support tool for stringed musical instruments making." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCD002.
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Ce travail de thèse propose un transfert de méthodes industrielles et de recherche que sont le prototypage virtuel et la caractérisation mécanique des structures vers l'artisanat d'art : la fabrication des instruments de musique à cordes, plus particulièrement la guitare et le violon.Ce domaine, historiquement éminemment empirique, est étudié ici avec des critères objectifs. Le travail porte principalement sur le comportementmécanique vibratoire de ces instruments de musique. Le comportement mécanique du matériau utilisé (bois de lutherie) est tout d'abord étudié, et une méthode non-destructive proposée et appliquée à l'épicéa et à l'érable. La fiabilité des modèles numériques et ensuite étudiée par des méthodes de vérification et de validation de modèle, habituellement utilisées dans les domaines industriels et de recherche Les modèles développés sont ensuite utilisés en support à l'étude de phénomènes complexes de l'acoustique musicale appliquée au violon et à la guitare. Pour finir, l'utilisation de ces méthodes numériques pour une application concrète en facture instrumentale (prise de décision en milieu incertain, innovation de la géométrie et des matériaux) est proposéeThis work proposes a methodology for the transfer of industrial and research domain methods toward arts and crafts domain. The virtual prototyping and mechanical characterization of materials are used for the stringed musical instruments making domain. The works is adressed to the guitar and violin making. This domain is historically driven by empricism and it is studied here using objective criteria. The main topic is the mechanical vibratory behaviour of musical instruments. Firstly, the mechanical behaviour of the material used (tonewood) is studied. A non-destructive methodology is proposed and applied on spruce and maple species. The reliability of the numerical models is studied by method usually used in industry and research, the verification and validation process. The models developed are used as a support for the study of complex phenomena in musical acoustics. Finally, the utilization of numerical method for a practical application in instrument making (decision support under uncertainties, geometric and material optimization) is proposed. The methodology for a transfer to art and crafts domain is discussed
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Arroyo, Molina Javier. "Towards a virtual climate chamber – A physical experimental study." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-282848.
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This project focuses on experimentally characterizing one of the tools used at Ericsson AB to test product performance, the climatic chamber. By conducting experiments inside the climate chamber and post processing the data obtained, the airflow inside it can be understood and compared to outdoor experimental data. One of the main sections of this work is to prove the hypothesis: The energy potential of the wind outdoors is greater than indoors, which is shown to be true when comparing values for the integral length scales of the flow, at the same mean wind speed. The second main part of this project is to obtain valuable experimental input that will serve to construct a virtual model of the climate chamber. With the conclusions drawn from the experiments, which involve heat transfer, boundary conditions for the numerical model can be established.Det här projektet fokuserar på att experimentellt karakterisera ett av verktygen som används i Ericsson AB för att testa produktprestanda - klimatkammaren. Genom att utföra experiment inuti klimatkammaren och efterbehandla de erhållna data, kan man få en förståelse för luftflödet inuti kammaren och jämföra resultat med experimentella data från utomhus. Ett av delmomenten i detta arbete bevisar hypotesen: 'Vindens energipotential är större än inomhus', vilket visar sig vara sant när man jämför värden för flödets integrala längdskalor, med samma medelvärde i vindhastighet. Den andra etappen av detta projekt är att erhålla en värdefull experimentell vägledning som kommer att tjäna till att konstruera en virtuell modell av klimatkammaren. Med slutsatserna från experimenten, som innefattar värmeöverföring, kan gränsvillkor för den numeriska modellen fastställas.
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Dumortier, Alexis Jean Louis. "Detection, classification and localization of seabed objects with a virtual time reversal mirror." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/55316.
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Thesis (S.M.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2009.Includes bibliographical references (p. 88-91).
The work presented in this thesis addresses the problem of the detection, classification and localization of seabed objects in shallow water environments using a time reversal approach in a bistatic configuration. The waveguide is insonified at low frequency ('kHz) with an omnidirectional source and the resulting scattered field is sampled by a receiving array towed behind an Autonomous Underwater Vehicle (AUV). The recorded signals are then processed to simulate onboard the AUV, the time reversed transmissions which serve to localize the origin of the scattered field on the seabed and estimate the position of the targets present. The clutter rejection based upon the analysis of the singular values of the Time Reversal operator is investigated with simulated data and field measurements collected off the coast of Palmaria (Italy) in January 2008.
by Alexis J. Dumortier.
S.M.
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Legros, Maxime. "Synthèse acoustique d'un module de ventilation automobile." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2295/document.
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La problématique de la qualité sonore à l'intérieur de l'habitacle est importante dans le domaine de l'automobile, particulièrement dans le cas des véhicules haut de gamme. La réduction du bruit des motorisations thermiques et l'émergence de solutions hybrides ou électriques ont transformé la perception du bruit par l'utilisateur. La contribution acoustique des équipements tels que le module de ventilation est devenue prépondérante et doit donc être étudiée dès la phase de conception. Afin de traiter la problématique acoustique et de fournir un outil de prototypage virtuel, ce travail a été mené dans le cadre du projet Cevas (Conception d'Equipement de Ventilation à Air Silencieux). Une approche de synthèse acoustique permet d'identifier les composants responsables du bruit produit et transmis. Leurs caractéristiques actives, traduites par un terme de source, et passives, traduites par un terme de perte par transmission, sont étudiées et représentées par des spectres en bandes fines. Cette définition permet la synthèse sonore du bruit produit et l'étude de la qualité sonore à l'aide de lois d'acceptation. Le ventilateur est la source principale d'un module de ventilation. Son terme de source est prédit par une loi originale, basée sur des données expérimentales et inspirée de la loi ASHRAE. Le terme de source du volet est caractérisé à l'aide de la méthode empirique de Nelson et Morphey. Le terme de source de l'échangeur thermique est déterminé à partir de mesures. Les termes de perte par transmission du volet et de l'échangeur thermique sont obtenus à l'aide de la matrice de diffusion expérimentale. L'environnement du milieu de propagation acoustique a une influence sur le bruit produit. La transposition des termes de source d’un environnement d'essai normalisé à un environnement représentatif des modules de ventilation a donc été étudiée. La méthode développée repose sur la modélisation du terme de source par une force volumique dont l'amplitude et la localisation sont indépendantes du milieu. Le développement de cette méthode a nécessité des modèles analytiques et numériques. L'application de la méthode pour un ventilateur placé dans un module de ventilation simplifié est confrontée à des essais. Un outil de prototypage virtuel est présenté pour un module de ventilation simplifié. La prédiction du bruit produit est confrontée à des mesures de puissance acoustique. L'usage de l'outil de prototypage permet d'étudier la contribution de chaque composant en considérant différents cas de ventilationThe sound quality problem inside the car cabin is important in the automotive field, especially in the case of upmarket vehicles. The reductions of the noise produced by internal combustion engines and the emergence of hybrid and electric solutions have transformed the perception of sound by the user. The acoustic contribution of equipment such as the HVAC has become paramount and must be studied from the design stage. In order to treat acoustic problems and provide virtual prototyping tools, t his thesis was conducted within the framework of the Cevas project (Conception d'Equipement de Ventilation à Air Silencieux) to study and characterize the components of an automotive HVAC. An acoustic synthesis approach is used to identify the components responsible for the noise generated and transmitted. Their active and passive properties, translated by a source term and a transmission loss, have been studied and represented by thin strips spectra. This definition allows sound synthesis of the noise produced and the study of sound quality using acceptance laws. The source term of the fan is predicted by an original law, based on experimental data and inspired by ASHRAE law. The source term of the flap is characterized by using the Nelson and Morphey empirical method. The source term of the heat exchanger is determined from measurements. The transmission losses of the flap and the heat exchanger are obtained using the scattering matrix. The transposition of the source terms from a standardized test environment to an acoustic medium representative of the HVAC has been studied. The developed method is based on modeling t he source term by acoustic excitation whose amplitude and location are independent of the environment. The application of this method has required analytical and numerical models to characterize the acoustic excitation. In the case of the fan, its propagation in a simplified HVAC is studied. A virtual prototyping tool has been implemented in the case of the simplified HVAC. The noise prediction is confronted with sound power measurements. The use of the prototyping tool allows studying the contribution of each component considering various cases of ventilation
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Forsman, Jimmy. "Game engine based auralization of airborne sound insulation." Thesis, Umeå universitet, Institutionen för fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-149498.
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Describing planned acoustic design by single number ratings yields a weak link to the subjective event, especially when the single number ratings are interpreted by others than experienced acousticians. When developing infrastructure, tools for decision making needs to address visual and aural perception. Visual perception can be addressed using game engines and this has enabled the establishment of tools for visualizations of planned constructions in virtual reality. Audio engines accounting for sound propagation in the game engine environment are steadily developing and have recently been made available. The aim of this project is to simulate airborne sound insulation by extending the support of recently developed audio engines directed towards virtual reality applications. The case studied was airborne sound insulation between two adjacent rooms in a building, the sound transmitted to the receiving room through the building structure resulting from sound pressure exciting the structural elements in the adjacent source room into vibration. The receiving room composed modelled space in the game engine Unreal Engine and Steam Audio was the considered audio engine. Sound transmission was modelled by filtering based on calculations of transmission loss via direct and flanking paths using the model included in the standard EN 12354-1. It was verified that the filtering technique for modelling sound transmission reproduced attenuations in correspondence with the predicted transmission loss. Methodology was established to quantify the quality of the audio engine room acoustics simulations. A room acoustics simulation was evaluated by comparing the reverberation time derived from simulation with theoretical predictions and the simulated reverberation time showed fair agreement with Eyring’s formula above its frequency threshold. The quality of the simulation of airborne sound insulation was evaluated relating the sound field in simulation to insulation classification by the standardized level difference. The spectrum of the simulated standardized level difference was compared with the corresponding sound transmission calculation for a modelled scenario. The simulated data displayed noticeable deviations from the transmission calculation, caused by the audio engine room acoustics simulation. However, the simulated data exhibited cancellation of favourable and unfavourable deviations from the transmission calculation resulting in a mean difference across the spectrum below the just noticeable difference of about 1 dB. Single number ratings was compared and the simulated single number rating was within the standard deviation of how the transmission model calculates predictions for a corresponding practical scenario measured in situ. Thus, the simulated data shows potential and comparisons between simulated data, established room acoustics simulation software and in situ measurements should further be made to deduce whether the deviations entails defects in the airborne sound insulation prediction or is an error imposed by the audio engine room acoustics simulation.
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Bai, Hequn. "Modèles hybrides pour la réverbération sonore." Thesis, Paris, ENST, 2016. http://www.theses.fr/2016ENST0009/document.
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Grâce au diverse applications prévues dans le divertissement, l’éducation et les domaines professionnels, la création d’un monde virtuel interactif a intéressé beaucoup de chercheurs dans l’académie et l’industrie. L’espace acoustique trois-dimensionnelle peut être synthétisé à partir de deux perspectives : les approches physiques et les approches perceptives. Méthode de transfert de rayonnement acoustique est une méthode efficace pour modéliser les réflexions diffuses et la réverbération tardive. Une extension de la méthode de transfert de rayonnement est proposée dans cette thèse, qui permet de modéliser les réflexions précoces et spéculaires, en conservant son avantage pour la simulation de réverbération tardive. Les approches perceptives utilisent des paramètres acoustiques pour modéliser la perception acoustique principale de l’environnement modélisé. Des réseaux récursifs de lignes à retard sont beaucoup utilisés pour générer de la réverbération tardive. Dans cette thèse, une nouvelle méthode est présentée, qui hérite l’efficacité de la structure des réseaux récursifs de lignes à retard, mais en le même temps, relie les paramètres des réseaux directement à la géométrie de l’environnement modélisé. Puis, l’approche physique et l’approche perceptive ont été combinées. La méthode de transfert de rayonnement acoustique simplifiée, avec extension à modéliser les réflexions spéculaires et diffuses, est incorporée à la structure des réseaux récursifs de lignes à retard. Le nouveau filtre réverbérant, en dépit de la modélisation des réfections diffuses et la réverbération tardive, est également capable de simuler les réflexions précoces et spéculaires avec précisionThere is an increasing interest in creating interactive virtual worlds due to the wide variety of potential applications in entertainment and education. The 3D acoustic scene can be synthesized from two perspectives : the physical approaches and the perceptual approaches. Acoustic radiance transfer method is an efficient ray-based method to model the diffuse reflections and the late reverberation. An extension of the Radiance Transfer Method (RTM) is proposed in this thesis, which allows modeling the early part of specular reflections while keeping the advantage of the original model for the late reverberation simulation. Feedback delay networks are widely used structures to generate the late reverberation. A new method is presented in this thesis, which inherits the efficiency of the Feedback Delay Network (FDN) structure, but aims at linking the parameters of the FDN directly to the geometries of the modeled environment. The relation is achieved by assigning a physical meaning to each delay line and studying the sound energy exchange between them. Then the physical approachand the perceptual approach are combined. The simplified acoustic Radiance Transfer Method, with extension for both specular and diffuse reflections, is incorporated with the Feedback Delay Networks. The new reverberator, despite of modeling the diffuse and late reverberation, is also capable of simulating the early and specular reflections with accuracy
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Soria, Sergio Gilberto Rodriguez. "Estudos sobre personalização da função de transferência relativa à cabeça em sistemas biaurais de reprodução acústica virtual." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-21032006-144134/.
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Este trabalho apresenta diversas propostas associadas ao uso ótimo de funções de transferência relativas à cabeça (HRTFs) em sistemas de reprodução acústica virtual por fones de ouvido. Estas propostas permitem personalizar a HRTF a indivíduos particulares, tomando como base uma combinação da modelagem estrutural e morfológica de HRTFs. Dentro do contexto da modelagem estrutural, o presente trabalho se concentrou no estudo da contribuição do pinna à HRTF. O pinna é a estrutura anatômica responsável pela percepção de elevação. Assim, o primeiro passo foi extrair um conjunto de funções de transferência relativas ao pinna (PRTFs) das HRTFs de uma base de dados. Para tanto, foram usadas diversas técnicas como análise preditiva linear para rastrear as ressonâncias, janelamento para eliminar a influência do torso, funções de autocorrelação e de atraso de grupo para salientar as antirressonâncias, e outros algoritmos para combinar ressonâncias e antirressonâncias em apenas uma magnitude espectral. Usando essa nova base de dados de PRTFs e parâmetros antropométricos propostos mais outros registrados na base de dados, um espaço vetorial correspondente à antropometria do pinna foi mapeado linearmente em um espaço vetorial correspondente às características espectrais da PRTF, calculando-se assim várias transformações lineares para estimação de novas PRTFs fora da base de dados. A estimação atingiu 66% de reconstrução no grupo de treino. O trabalho está orientado à exploração das características espectrais importantes na percepção de elevação, portanto, está limitado ao plano médio do hemisfério frontal, onde não existem diferenças interaurais significativas nem efeitos difrativos da cabeça. Finalmente é proposto um sistema de testes de localização de fonte sonora para validar o modelo.This work presents several proposals associated with the optimal use of head-related transfer functions (HRTF) in virtual auditory spaces presented via headphones. These proposals lead to personalization of the HRTF to particular individuals, using a combination of the structural and morphological modeling techniques. In the context of structural modeling, this work focuses on modeling the contribution of the pinna to the HRTF. The pinna is the anatomical structure responsible for vertical sound localization. Thus, the first step was to extract a set of pinna-related transfer functions (PRTFs) from HRTFs published in a database. This was accomplished using several techniques like linear prediction analysis for tracking the resonances, windowing for eliminating the torso influence, autocorrelation and group delay functions for emphasizing the notches and other algorithms for combining resonances and notches in only one magnitude response. Using this novel database of PRTFs and a set of proposed anthropometric parameters plus some others registered in the database, a vector space corresponding to pinna anthropometry is linearly mapped into a vector space corresponding to spectral features of the PRTF, being calculated, in this way, several linear transformations for estimation of new PRTFs, outside the database. The estimation attains 66% of reconstruction in the training group. The work focuses on the exploration of spectral characteristics important for elevation perception, therefore, it is limited to the median plane where there are no meaningful interaural differences nor head diffraction effects. Finally, a system for sound localization tests is proposed in order to validate the model.
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Quintana, James R. A. "Frequency Responsive Beam Tracing." Oberlin College Honors Theses / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1462957979.
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Hill, Adam J. "Analysis, modeling and wide-area spatiotemporal control of low-frequency sound reproduction." Thesis, University of Essex, 2012. http://hdl.handle.net/10545/230034.
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This research aims to develop a low-frequency response control methodology capable of delivering a consistent spectral and temporal response over a wide listening area. Low-frequency room acoustics are naturally plagued by room-modes, a result of standing waves at frequencies with wavelengths that are integer multiples of one or more room dimension. The standing wave pattern is different for each modal frequency, causing a complicated sound field exhibiting a highly position-dependent frequency response. Enhanced systems are investigated with multiple degrees of freedom (independently-controllable sound radiating sources) to provide adequate low-frequency response control. The proposed solution, termed a chameleon subwoofer array or CSA, adopts the most advantageous aspects of existing room-mode correction methodologies while emphasizing efficiency and practicality. Multiple degrees of freedom are ideally achieved by employing what is designated a hybrid subwoofer, which provides four orthogonal degrees of freedom configured within a modest-sized enclosure. The CSA software algorithm integrates both objective and subjective measures to address listener preferences including the possibility of individual real-time control. CSAs and existing techniques are evaluated within a novel acoustical modeling system (FDTD simulation toolbox) developed to meet the requirements of this research. Extensive virtual development of CSAs has led to experimentation using a prototype hybrid subwoofer. The resulting performance is in line with the simulations, whereby variance across a wide listening area is reduced by over 50% with only four degrees of freedom. A supplemental novel correction algorithm addresses correction issues at select narrow frequency bands. These frequencies are filtered from the signal and replaced using virtual bass to maintain all aural information, a psychoacoustical effect giving the impression of low-frequency. Virtual bass is synthesized using an original hybrid approach combining two mainstream synthesis procedures while suppressing each method‟s inherent weaknesses. This algorithm is demonstrated to improve CSA output efficiency while maintaining acceptable subjective performance.
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Barba, Sevillano Arturo. "La acústica virtual como herramienta arqueológica. Historia y sonido en el Teatro Principal de Valencia." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/62687.
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[EN] This thesis takes the Teatro Principal Valencia as a sample of study and raises questions to deepen the awareness of its history, architecture and acoustics. Our final objective has been to analyse and reconstruct the acoustic conditions of our theatre in different historical moments, providing a new way of approaching the Valencian architectural heritage with it. In addition to this, we intend to show the potentiality of our current tools of acoustic simulation and auralization for the study of the most widely deployed theatrical architectural typology in Europe in the seventeenth century: Italian baroque theatre.
The Teatro Principal Valencia is a representative example of an Italian-style theatre because of meeting each and every formal characteristic that define this building typology. Inaugurated in the year 1832, it is the oldest theatre in Valencia and one of Spain's oldest Italian-style venues, prior even to pioneer projects of the Teatro Real de Madrid (1850), and the Gran Teatre del Liceu de Barcelona (1847).
We have carried out archive research data, the screening of press, bibliographical research, as well as document consultation and compilation, planimetry and images (many of them unpublished), which have made the recovery of the history of the Valencian theatrical venue possible, blurred with the passing of time. That represented in itself an objective of this thesis, and as such it is presented in the section on results. This detailed historical study of our theatre has allowed us to select five moments in which its morphological differences could manifest changes in its acoustics: 1832, 1859, 1928, 1968, and 2015.
Normalised acoustic measures have been carried out in the Teatro Principal, and we have developed three-dimensional computer models of the five selected morphologies. The current acoustic model has been adjusted with measures on-site. From the aforementioned model, volumetric, geometric measurements and absorption and/or diffusion coefficients have been introduced with the object of virtually revert each architectural intervention that our theatre has experienced, always basing ourselves on documented historical criteria. All of this has allowed us to rebuild the sonic history of the Teatro Principal Valencia, being able to compare the changes that its acoustic parameters have experienced in more than 180 years of its life.
As a key outcome to this thesis, the geometrical model of the Teatro Principal has been studied thoroughly on its graphics realism through the use of texturization techniques and virtual photorealistic rendering, achieving a model that can experiment on auralizations in a striking immersive graphic environment (CAVE, PowerWall, etc.), opening the door to new lines of research.[ES] Este trabajo toma el Teatro Principal de Valencia como materia de estudio y plantea profundizar en el conocimiento de su historia, arquitectura y acústica. Nuestro objetivo final ha sido analizar y reconstruir las condiciones acústicas del teatro en diversos momentos históricos, aportando con ello una novedosa forma de acercamiento al patrimonio arquitectónico valenciano. Pretendemos, además, mostrar la potencialidad de las actuales herramientas de simulación acústica y auralización para el estudio de la tipología arquitectónica teatral más extendida en Europa desde el siglo XVII: el teatro barroco a la italiana. El Teatro Principal de Valencia es un ejemplo paradigmático de teatro a la italiana al reunir todas y cada una de las características formales que definen esta tipología edilicia. Inaugurado en el año 1832, es el decano de los teatros valencianos y uno de los recintos a la italiana en activo más antiguos de España, anterior incluso a los proyectos pioneros del Teatro Real de Madrid (1850) y del Gran Teatre del Liceu de Barcelona (1847). Hemos llevado a cabo trabajos de búsqueda en archivo, vaciados de prensa, investigación bibliográfica, así como consulta y recopilación de documentos, planimetría e imágenes (inéditas muchas de ellas) que han hecho posible la recuperación de la historia del recinto teatral valenciano, desdibujada en gran medida por el paso del tiempo. Todo ello ha constituido en sí mismo un objetivo de esta tesis, y como tal se presenta en el apartado de resultados. Este estudio histórico pormenorizado del teatro nos ha permitido seleccionar cinco momentos en los que sus diferencias morfológicas podrían poner de manifiesto cambios en su acústica: 1832, 1859, 1928, 1968 y 2015. Se han realizado medidas acústicas normalizadas en el teatro y hemos desarrollado modelos informáticos tridimensionales de las cinco morfologías seleccionadas. El modelo acústico actual ha sido ajustado con las medidas in situ. A partir de dicho modelo, se han introducido modificaciones volumétricas, geométricas y de coeficientes de absorción y/o difusión con objeto de revertir virtualmente cada una de las intervenciones arquitectónicas que ha experimentado la sala teatral, siempre basándonos en criterios históricos documentados. Todo ello nos ha permitido reconstruir la historia sonora del Teatro Principal de Valencia, pudiendo comparar los cambios que sus parámetros acústicos han experimentado en sus más de 180 años de vida. Como colofón a la tesis, se ha profundizado en el realismo gráfico del modelo geométrico del Teatro Principal actual mediante el empleo de técnicas de texturización y realidad virtual fotorrealística, habiendo conseguido un modelo que permite experimentar auralizaciones del Teatro Principal en un impactante entorno gráfico inmersivo (CAVE, ProwerWall, etc.) que abre la puerta a nuevas líneas de investigación.
[CAT] Aquest treball pren el Teatre Principal de València com a matèria d'estudi i planteja aprofundir en el coneixement de la seua història, arquitectura i acústica. El nostre objectiu final ha estat analitzar i reconstruir les condicions acústiques del teatre en diversos moments històrics, aportant amb això una nova forma d' apropar-nos al patrimoni arquitectònic valencià. Pretenem, a més, mostrar la potencialitat de les actuals eines de simulació acústica i auralització per a l' estudi de la tipologia arquitectònica teatral més estesa a Europa des del segle XVII: el teatre barroc a la italiana. El Teatre Principal de València és un exemple paradigmàtic de teatre a la italiana ja que reuneix totes i cadascuna de les característiques formals que defineixen aquesta tipologia edilícia. Inaugurat l 'any 1832, es tracta del degà dels teatres valencians i un dels més antics d'Espanya, anterior fins i tot als projectes pioners del Teatro Real de Madrid (1850) i del Gran Teatre del Liceu de Barcelona (1847). Hem dut a terme treballs de recerca en arxiu, buidats de premsa, recerca bibliogràfica, així com consulta i recopilació de documents, planimetria i imatges (moltes inèdites) que han fet possible la recuperació de la història del recinte teatral valencià, desdibuixada en gran mesura pel pas del temps. Tot això ha constituït en si mateix un objectiu d' aquesta tesi, i com a tal l' hem presentat en l' apartat de resultats. Aquest estudi històric del teatre ens ha permès seleccionar cinc moments en què les seues diferències morfològiques podrien posar de manifest canvis en la seua acústica: 1832, 1859, 1928, 1968 i 2015. S'han realitzat mesures acústiques normalitzades al teatre i hem desenvolupat models informàtics tridimensionals de les cinc morfologies seleccionades. El model acústic actual ha estat ajustat amb les mesures in situ. A partir d'aquest model, s'han introduït modificacions volumètriques, geomètriques i de coeficients d'absorció i / o difusió a fi de revertir virtualment cadascuna de les intervencions arquitectòniques que ha experimentat la sala teatral, sempre basant-nos en criteris històrics documentats. Així hem pogut reconstruir la història sonora del Teatre Principal de València i comparar els canvis que els seus paràmetres acústics han experimentat al llarg de la seua vida. Com a colofó de la tesi, hem aprofundit en el realisme gràfic del model geomètric del Teatre Principal actual mitjançant l' ús de tècniques de texturització i realitat virtual fotorealística, havent desenvolupat un model que permet experimentar auralitzacions del Teatre Principal en un impactant entorn gràfic immersiu (CAVE, ProwerWall, etc.) que ens obri la porta a noves línies d' investigació.
Barba Sevillano, A. (2016). La acústica virtual como herramienta arqueológica. Historia y sonido en el Teatro Principal de Valencia [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62687
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Gardner, William G. "The virtual acoustic room." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/66351.
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Carmo, Rodrigo Salvadori Baptista do. "Ambiente virtual de aprendizagem em ondas e acústica para auxiliar o processo ensino e aprendizagem da física no ensino médio." Universidade Federal de São Carlos, 2013. https://repositorio.ufscar.br/handle/ufscar/4439.
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Previous issue date: 2013-02-03This work describes the development of a VLE Virtual Learning Environment, where music is the basis for studying sound waves. New educational tools such as videos, animations, simulations, as well as the Moodle platform, were used to create a virtual environment, where students can learn about sound waves in an autonomous and interactive way, motivating them to use computers and internet as facilitators of the teaching/learning process, making it more effective and interesting. This material was applied to High School students - which translates to Ensino Médio and/or Pré-Vestibular in Brazil s schooling system - in the following schools: Carlos Drummond de Andrade and Nomelini Cirandinha, both in Barretos, Escola Espaço Livre, in Bebedouro and Coc Cardiofísico, in Jaboticabal. Both the teaching experience related to the VLE construction and its learning results are also described in this work.
O presente trabalho descreve o desenvolvimento de um AVA Ambiente Virtual de Aprendizagem, onde utilizamos a música como fio condutor para o estudo das ondas sonoras. Fazendo uso das novas ferramentas educacionais como vídeos, animações, simulações bem como a plataforma Moodle, produzimos um ambiente virtual onde os alunos podem estudar as ondas sonoras de uma forma interativa e autônoma, incentivando-os a utilizar o computador e a internet como facilitadores do processo de ensino/aprendizagem, tornando este processo mais efetivo e interessante. Esse material foi aplicado a turmas de alunos do Ensino Médio e Pré-Vestibular das escolas Carlos Drummond de Andrade e Nomelini Cirandinha, ambas de Barretos, Escola Espaço Livre, de Bebedouro e escola COC Cardiofísico, de Jaboticabal. Tanto a experiência didática quanto a construção do AVA e seus resultados de aprendizagem são também descritos neste trabalho.
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Gardner, Michael D. "Scan-Based Near-Field Acoustical Holography on Partially Correlated Sources." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3167.pdf.
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Rose, John Frederick William. "Visually adaptive virtual acoustic imaging." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399992.
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Oxnard, Stephen. "Efficient hybrid virtual room acoustic modelling." Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/17459/.
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This thesis investigates approaches to virtual room acoustic modelling and auralisation in order to a develop hybrid modelling solution that is capable of efficient and accurate simulation of enclosed sound propagation. Emphasis is placed on the advantages and disadvantages of state of the art numerical and geometric acoustic modelling methods. Numerical methods have been shown to preserve important sound wave characteristics such as diffraction and room modes, and are considered more accurate for low frequency acoustic modelling than geometric techniques which fail to preserve such wave effects. However, the implementation of numerical acoustic models inherently requires large computational effort compared to more efficient geometric techniques such as ray-tracing. This is particularly problematic for simulations of large-scale 3D acoustic environments and for high spatio-temporal sampling rates. A novel acoustic modelling solution is presented, which seeks to circumvent the disadvantageous computational requirements of 3D numerical models while producing a suitable approximation to low frequency sound behaviour. This modelling technique incorporates multiple planar cross-sectional 2D Finite Difference schemes that are utilised in combination to synthesise low frequency wave propagation throughout the target acoustic field. In this way a subset of prominent low frequency sound wave characteristics may be emulated with low computational cost compared to 3D numerical schemes. These low-frequency results can then be combined with the high-frequency output from efficient geometric simulations to create a hybrid model providing accurate broadband results at a relatively low computational cost. Investigation of room impulse response rendering for a series of theoretic and real spaces demonstrates advantages of this new hybrid acoustic modelling technique over purely ray-based methods in terms of low frequency accuracy, and over 3D numerical methods in terms of computational efficiency. Conclusions are drawn from objective measurements obtained from simulation results of the virtual models produced. Results demonstrate the applicability of the novel hybrid approach to the enhancement of purely ray-based room impulse response rendering by which a more realistic representation of low frequency wave phenomena may be simulated in an efficient manner, improving the theoretical accuracy of objective and audible results. This study contributes towards research and design of high-speed, interactive virtual acoustic simulations appropriate for industrial and creative virtual reality applications.
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Postma, Barteld. "Serious auralizations." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS091/document.
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Au cours des dernières décennies, la présence des auralisations dans l’acoustique architecturale et la réalité virtuelle est devenue de plus en plus importante. De nombreuses applications en découlent, telles que les explorations de la réalité virtuelle multimodale ou les études de l’influence acoustique des rénovations et la recherche historique. Malgré ces nombreux cas d’utilisation, peu d’études scientifiques ont été réalisées sur le sujet. L’objectif de cette thèse était donc d’examiner l’utilisation d’auralisations acoustiques de salles, basées sur l’acoustique géométrique (GA) comme outil scientifique et visant à aider à la création d’auralisations historiquement exactes plus écologiquement valables. Déjà dans les années 1930 les premières tentatives ont été entreprises pour rendre audible (de manière imaginaire) les champs sonores. Les développements au cours des 80 dernières années ont conduit à des améliorations significatives des auralisations. Aujourd’hui, si l’on veut créer des auralisations, l’enregistrement anéchoïque réalisé préalablement doit être convolué avec une réponse impulsionnelle ambiante, mesurée ou simulée (RIR). Les logiciels GA sont souvent utilisés pour calculer numériquement la RIR de géométries compliquées. Les méthodes basées sur les ondes sont gourmandes en calcul, nécessitant des modèles géométriques complexes et des données d’entrée complexes. Cette thèse vise à améliorer la qualité des auralisations entièrement calculées. À cette fin, on a étudié l’étalonnage des modèles acoustiques des salles et l’inclusion de la directivité vocale dynamique. Des mesures acoustiques de la pièce ont été réalisées dans quatre salles et des modèles d’acoustique géométrique ont été créés des mêmes espaces. Une procédure méthodique de calibration du modèle a été proposée, réalisée dans les quatre salles, et validée au préalable par comparaison d’estimation de paramètres. Des tests d’écoute subjectifs comparant des auralisations mesurée set simulées pour trois espaces différents ont révélé que les auralisations étaient également perçues pour huit attributs acoustiques évalués. Par la suite, un cadre permettant d’inclure la directivité vocale dynamique a été présenté. Les résultats des tests d’écoute ont montré des différences perceptuelles entre la directivité vocale dynamique et la directivité de source statique pour la plausibilité, l’enveloppement de l’auralisation ainsi que la largeur perçue de la source. L’amélioration de la validité écologique des auralisations a permis d’étudier l’influence des visualisations sur l’expérience acoustique, avec un degré de confiance raisonnable que les effets perçus sont également applicables dans des situations réelles. À cet effet, un cadre a été établi qui a permis des évaluations multimodales de pièces de théâtre et de concerts. Les résultats d’un test d’écoute multi-modal présentant une scène cohérente visuelle-sonore ont confirmé les différences perceptuelles entre les auralisations de directivité vocale dynamique et statique. Dans ce même cadre, un second test d’écoute comparant des scènes visuelles/sonores incohérentes è cohérentes, indiquait qu’avec une distance source-récepteur accrue, les auralisations sont perçues acoustiquement plus éloignées et plus élevéeOver recent decades, auralizations have become more prevalent in architectural acoustics and virtual reality. Auralizations have numerous use-cases such as multi-modal virtual reality explorations, studies of the acoustical influence of renovations, and historic research. Despite their numerous use-cases, they rarely have been part of scientific studies. Therefore, the goal of this thesis was to examine the use of room acoustical auralizations based on geometrical acoustics (GA) as a scientific tool and aimed to aid in the creation of more ecologically valid historically accurate auralizations. Already in the 1930s first attempts were undertaken to render audible (imaginary) sound fields. Developments over the last 80 years have led to significant improvements of auralizations. Today, if one wishes to create auralizations, generally anechoic recording need to be convolved with either a measured or simulated room impulse response (RIR). GA software are often employed to numerically compute the RIR of complicated geometries. Wave-based methods are computationally intensive, requiring complex geometrical models and complex input data. This thesis aims to enhance the quality of fully computed auralizations. For this purpose the calibration of room acoustical models and the inclusion of dynamic voice directivity were studied. Room acoustical measurements were carried out in four rooms and geometrical acoustics models were created of the same spaces. A methodical calibration procedure was proposed, carried out in the four rooms, and first validated by means of parameter estimation comparison. Subjective listening tests which compared measured and simulated auralizations for three spaces found that the auralizations were equally perceived for 8 tested acoustical attributes. Subsequently, a framework was presented which enabled the inclusion of dynamic voice directivity. The results of listening tests indicated that perceptual differences between dynamic voice directivity and regular static source ordinations in plausibility and envelopment of the auralization as well as perceived width of the source. With the improved ecological validity of the auralizations it was possible to study the influence of visualizations on the acoustical experience, with a reasonable degree of confidence that perceived effects are also applicable in real-life situations. For this purpose, a framework was established which enabled multi-model assessments of theater plays and concerts. Results of a visual-aural coherent multi-modal listening test confirmed the perceptual differences between dynamic and static voice directivity auralizations. A second listening test employing this framework which compared incoherent to coherent aural-visual cues indicated that with increased visual source-receiver distance auralizations are perceived acoustically more distant and louder
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Papadopoulos, Timoleon. "Inverse filtering for virtual acoustic imaging systems." Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/157421/.
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The research topic of this thesis is the use of inverse filtering for the design and implementation of two-channel virtual acoustic imaging systems that utilise loudspeakers. The basic objective of such systems is to invert the electroacoustic plant between the input to the loudspeakers and the output at the listener’s ears and hence make it possible for a pair of binaural signals to be locally reproduced at the position of the listener’s ears. As a starting point for the research presented, a previously introduced type of inverse filtering design is considered in which the inverse is implemented with FIR filters. The basic formulation of this design is described and a number of innovative points regarding its implementation are made. An experimental procedure is then formulated for the evaluation of the effectiveness of this inverse filtering design that is based on objective measurements of the inversion process. Unlike previously employed methods that are based on computer simulations or subjective experiments, the introduced experimental procedure is shown to be very efficient in isolating and exactly quantifying the effect on the accuracy of the inversion of a number of errors and approximations typically present in the implementation. A detailed evaluation is thus presented of the inverse filtering design at hand in realistic conditions of implementation. Subsequently, a novel method for the off-line implementation of the inverse filtering is presented that utilises recursive filters of lower order. In this method, the responses of the inverse filters are decomposed into two parts, one realisable in forward time and one in backward time. The effectiveness of this new method for the implementation of the inverse is tested and compared with a small selection of the objective evaluation results described above. Finally, an algorithm for the on-line implementation of the forward-backward inverse filtering is proposed and its computational cost is compared with the currently available frequency-domain block-processing filtering algorithms.
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Hoag, Kenneth J. "Facilitating rich acoustical environments in virtual worlds." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1998. http://handle.dtic.mil/100.2/ADA354946.
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Thesis (M.S. in Computer Science) Naval Postgraduate School, September 1998.Thesis advisor(s):, Rudolph P. Darken. "September 1998." Includes bibliographical references (p. 77-79). Also available online.
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MAFFRA, SERGIO ALVARES RODRIGUES DE SOUZA. "PROPAGATION OF SOUND IN TWO-DIMENSIONAL VIRTUAL ACOUSTIC ENVIRONMENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=3723@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORDurante muito tempo, a simulação computacional de fenômenos acústicos tem sido utilizada principalmente no projeto e estudo da acústica de ambientes. Recentemente, no entanto, podemos ver um maior interesse na utilização dessas simulações como forma de aumentar a sensação de imersão em ambientes virtuais. De forma geral, podemos dizer que um ambiente acústico virtual deve ser capaz de realizar duas tarefas: simular a propagação do som em um ambiente e ser capaz de reproduzi-lo com seu conteúdo espacial, isto é, reproduzi-lo de forma a permitir o reconhecimento da direção de propagação do som. Esta dissertação trata desses dois assuntos. São revistos os algoritmos mais comuns para o cálculo da propagação do som e, brevemente, as formas utilizadas para reproduzir áudio com conteúdo espacial. Também é apresentada a implementação de um ambiente acústico virtual, baseado nos algoritmos de beam tracing, que simula a propagação do som em ambientes bidimensionais. Como grande parte do cálculo de propagação é realizada em uma etapa de pré-processamento, o ambiente acústico virtual implementado trata apenas de fontes fixas no espaço. Os caminhos de propagação calculados são compostos de reflexões especulares e difrações do som.
For a long time, computational simulation of acoustic phenomena has been used mainly in the design and study of the acoustic properties of concert and lecture halls. Recently, however, there is a growing interest in the use of such simulations in virtual environments in order to enhance users` immersion experience. Generally, we can say that a virtual acoustic environment must be able to accomplish two tasks: simulating the propagation of sound in an environment and reproducing audio with spatial content, that is, in a way that it allows the recognition of the direction of sound propagation. These tasks are the topic of the present dissertation. We begin with a revision of the most common algorithms for the simulation of sound propagation and, briefly, of the reproduction of audio with spatial content. We then present the implementation of a virtual acoustic environment, based on beam tracing algorithms, which simulates the propagation of sound waves in two-dimensional environments. As most of the computation is made in a pre-processing stage, the virtual acoustic environment implemented is appropriate only for spatially fixed sound sources. The propagation paths computed are made of specular reflections and of diffractions.
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Foteinou, Aglaia. "Perception of objective parameter variations in virtual acoustic spaces." Thesis, University of York, 2013. http://etheses.whiterose.ac.uk/5628/.
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This thesis investigates if reliability in objective acoustic metrics obtained for an auralized space implies accuracy and reliability in terms of the subjective listening experience. Auralizations can be created based either on impulse response measurements of an existing space, or simulations using computer-based acoustic models. Validations of these methods usually focus on the observation of standard objective acoustic measures and how these vary under certain conditions. However, for accurate and believable auralization, the subjective quality of the resulting virtual auditory environment should be considered as being at least as important, if not more so. This study is focused in the most part on St. Margaret’s Church, York, UK. Impulse responses have been acquired in the actual space and virtual acoustic models created using CATT-Acoustic and ODEON-Auditorium auralization software, both based on geometric acoustic algorithms. Variations in objective acoustic parameters are examined by changing the physical characteristics of the space, the receiver position and the sound source orientation. It is hypothesised that the perceptual accuracy of the auralizations depends on optimising the model to minimise observed changes in objective acoustic parameters. This objective evaluation is used to ascertain the behaviour of certain standard acoustic parameters. From these results, impulse responses with suitable acoustic values are selected for subjective evaluation via listening tests. These acoustic parameters, in combination with the physical factors that influence them, are examined, and the importance of variation in these values in relation to our perception of the result is investigated. Conclusions are drawn for both measurement and modelling approaches, demonstrating that model optimisation based on key acoustic parameters is not sufficient to guarantee perceptual accuracy as perceptual differences are still evident when only a simple acoustic parameter demonstrates a difference of greater than 1 JND. It is also essential to add that the overall perception of the changes in the acoustic parameters is independent of the auralization technique used. These results aim to give some confidence to acoustic designers working in architectural and archeoacoustic design in terms of how their models might be best created for optimal perceptual presentation.
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Pope, Jackson. "Multi-sensory rendering for the exploration of virtual environments." Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326690.
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Chun, Ingyu. "A numerical study of multichannel systems for the presentation of virtual acoustic environments." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402400.
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Kawano, Rafael Rogora. "Prototipagem virtual sonora aplicada a ruido de martelamento de pneumaticos automotivos." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263368.
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Orientador: Jose Roberto de França ArrudaDissertação ( mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Neste trabalho foi explorado o mecanismo de geração de ruído de pneumáticos automotivos conhecido como ruído de martelamento, segundo a abordagem da Prototipagem Virtual Sonora. Foi implementado um modelo teórico disponível na literatura que considera apenas a pluralidade de passos de blocos na banda de rodagem. A partir dele, dois outros modelos foram desenvolvidos e implementados considerando, além da pluralidade de passos de blocos, os efeitos do contato pneu/pavimento (distribuição da pressão de contato), da multiplicidade de carreiras de blocos, da defasagem helicoidal entre as carreiras e da deflexão sob carga e a definição de um perfil do sinal de excitação dos blocos. A sensibilidade da resposta temporal e espectral aos parâmetros dos modelos foi avaliada. Modelos de caminhos estruturais foram implementados e se basearam em dados experimentais. Por fim, o programa desenvolvido sintetiza o ruído virtual gerado pelo contato pneu/pavimento para diferentes configurações do pneu previstas pela modelagem, podendo ser ouvido através de fones de ouvido e permitindo a realização de uma análise subjetiva.
Abstract: This study explored the automotive tire noise generation mechanism known as hammer noise, according to the Virtual Acoustic Prototyping approach. A theoretical model available in the literature that considers only the plurality of block pitches in the tread band was implemented. Based on this model, two improved models were developed and implemented considering, besides the plurality of block pitches, the effects of the tire / pavement contact (contact pressure distribution), the number of block ribs, the helical gap of the careers, the deflection of the tire under load and the definition of a profile of the resulting excitation signal. The sensitivity of the response in the time and frequency domains to the tire parameters was evaluated. Models of structural borne paths based on experimental data were implemented. Finally, the program developed synthesizes the virtual noise generated by the tire / pavement contact for different configurations of the tire, which can be listened in headphones, thus enabling a subjective analysis of hammer noise.
Mestrado
Mecanica dos Solidos
Mestre em Engenharia Mecânica
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Reed, Darrin Kiyoshi. "Virtual audio localization with simulated early-reflections and generalized head-related transfer functions." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/reed/ReedD1209.pdf.
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In a natural sonic environment a listener is accustomed to hearing reflections and reverberation. It is conceived that early reflections could reduce front-back confusion in synthetic 3-D audio. This thesis describes experiments which seek to determine whether or not simulated reflections can reduce front-back confusions for audio presented with non-individualized head-related transfer functions (HRTFs) via headphones. To measure the contribution of the reflections, 13 human subjects participated in localization experiments which compared their localization ability with anechoic HRTF processing versus HRTF processing with a single early-reflection. The results were highly subject dependent; some showed improvement while others seemed to be inhibited by the reflections. Statistical analysis of the overall results concluded that a single reflection does not provide a significant difference in localization ability. Although this data rejects the hypothesis of this investigation, some suspicion regarding the contribution of lateral reflections in an auditory environment remains.
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Galgenmüller, Sabrina [Verfasser]. "Acoustic Radiation Force Imaging der Leber - Generierung von Normwerten und Vergleich der Virtual Touch Tissue Quantification und Virtual Touch Imaging Quantification / Sabrina Galgenmüller." Ulm : Universität Ulm. Medizinische Fakultät, 2016. http://d-nb.info/1091060924/34.
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Nicol, Rozenn. "Représentation et perception des espaces auditifs virtuels." Habilitation à diriger des recherches, Université du Maine, 2010. http://tel.archives-ouvertes.fr/tel-01066312.
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Un espace auditif virtuel (par référence à l'acronyme anglais VAS pour Virtual Auditory Space) est une scène sonore virtuelle constituée d'un ensemble de sources sonores qui n'existent que dans l'espace perceptif de l'auditeur. Cet espace est généré au moyen des technologies de spatialisation sonore (telles que : stéréophonie, technologie binaurale, Wave Field Synthesis ou Higher Order Ambisonics) qui reposent sur des modèles de représentation de la scène sonore. La modélisation est le premier aspect à étudier et concerne notamment les étapes de la captation et de la restitution de l'information spatiale. La notion de format audio spatialeé (et par la même les questions de conversion de format et de compression) est implicite. A l'autre extrémité se situe la perception de l'espace ainsi généré pour évaluer comment l'auditeur perçoit les sources sonores virtuelles. Ce mémoire ouvre une réflexion sur ces différentes problèmatiques. En complément d'un état des lieux des connaissances actuelles, deux questions sont traitées en détails. La première question porte sur les technologies de spatialisation multi haut-parleurs en se focalisant sur les technologies Wave Field Synthesis (WFS) et Higher Order Ambisonics (HOA). Il est montré quel(s) système(s) concret(s) peuvent être mis en oeuvre à partir des équations théoriques. Grâce à un formalisme unifié les convergences entre les deux technologies sont mises en évidence, pour ouvrir sur une évaluation comparée. La seconde question concerne l'application de la spatialisation sonore à des terminaux individuels (c'est à dire mono auditeur) et portables, impliquant de façon préférentielle un rendu sur casque. Il s'agit du domaine de la technologie binaurale qui consiste à reproduire les signaux acoustiques à l'entrée des conduits auditifs. Cette technologie repose principalement sur la reproduction des indices de localisation qui résultent de l'interaction des ondes acoustiques avec le corps de l'auditeur et sont par la même fortement individuels. Il est décrit comment modéliser ces indices (notamment les informations temporelles correspondant à l'Interaural Time Difference ou ITD et les informations spectrales associées aux Indices Spectraux ou IS) et comment individualiser cette modélisation.
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Whiting, Jennifer Kay. "Development of a Real-Time Auralization System for Assessment of Vocal Effort in Virtual-Acoustic Environments." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7056.
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This thesis describes the development of the real-time convolution system (RTCS) for a little-studied talker/listener in virtual acoustic environments. We include descriptions of the high-resolution directivity measurements of human speech, the RTCS system components, the measurement and characterization of oral-binaural room impulse responses (OBRIRs) for a variety of acoustic environments, and the compensation filter necessary for its validity. In addition to incorporating the high-resolution directivity measurements, this RTCS improved on that developed by Cabrera et al. [1] through the derivation and inclusion of the compensation filter. Objective measures in the time- and frequency-domains, as well as subjective measures, were developed to asses the validity of the RTCS. The utility of the RTCS is demonstrated in the study on vocal effort, and the results of an initial investigation into the vocal effort data are presented.
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Forget, Sandra. "Reconstruction des champs acoustiques sur structure à géométrie complexe en environnement non contrôlé, hiérarchisation de sources et corrélation éléments finis : Application sur un Groupe Moto Propulseur d’automobile." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI122.
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Pour limiter la pollution sonore et répondre aux exigences des clients, le secteur automobile est contraint pour la prochaine décennie à diminuer drastiquement les émissions sonores de ses véhicules. Le Groupe Moto Propulseur (GMP) constitue l’une des principales sources de bruit et les solutions palliatives couteuses ne permettront plus à terme le passage des normes acoustiques. L’optimisation du comportement vibro-acoustique de telles structures par un travail détaillé de la conception reste le meilleur levier. Dans ce contexte, les ingénieurs sont à la recherche de méthodes expérimentales d’identification et de caractérisation de sources acoustiques particulièrement efficaces et pertinentes. En ce sens, la principale attente est la reconstruction précise des champs acoustiques sur des structures à géométrie complexe en présence d’un environnement industriel contraignant et non contrôlé. Dans la continuité de la méthode u-iPTF (inverse Patch Transfer Functions) précédemment développée, la première partie de ce travail de doctorat s’est attachée à uniformiser le principe du volume acoustique virtuel sur lequel elle repose afin de proposer la formulation d’une méthode alternative, dénommée m-iPTF, dont le principe théorique permet de répondre intégralement au cahier des charges du partenaire industriel. En effet, contrairement à la méthode u-iPTF, la méthode m-iPTF s’affranchit de la mesure des vitesses de particules d’air, encore peu robuste et coûteuse, et utilise uniquement des pressions acoustiques. Une première étude numérique a cadré le domaine de validité et de mise en application de la méthode. Elle a été suivie par trois campagnes expérimentales de complexité croissante dont une application en conditions industrielles standards, celle d’un GMP complet fonctionnant sur banc moteur. L’ensemble de ces études a permis de démontrer l’adéquation de la méthode à un milieu industriel et d’illustrer toutes les potentialités offertes par la reconstruction 3D de champs pariétaux pour l’optimisation de structures complexes (discrimination et hiérarchisation de sources, corrélation et couplage à la simulation numérique...)To limit the sound pollution and to meet customer requirements, the automotive sector is constrained for the next decade to drastically reduce the noise emissions of its vehicles. The powertrain is one of the main sources of noise and expensive workaround will not be sufficient in the future to meet acoustic standards. The optimization of the vibro-acoustic behavior of such structures by a detailed design work remains the best way. In this context, engineers are looking for an efficient and relevant experimental noise source identification and characterization method. In this sense, the main expectation is the precise reconstruction of all the acoustic source fields on geometrically complex structures and in the presence of a restrictive and uncontrolled industrial environment. In the continuity of the u-iPTF method (inverse Patch Transfer Functions) previously developed, the first part of this PhD work was to standardize the principle of the virtual acoustic volume on which it relies and to propose the development of an alternative method, called m-iPTF, whose theoretical principle allows reaching all the specifications of the industrial partner. Indeed, contrary to the u-IPTF method, the m-iPTF method overcomes the measurement of air particles velocity, expensive and not yet robust, and uses acoustic pressure only. A first numerical study framed the scope of validity and application of the method. It was followed by three experimental campaigns of increasing complexity with a final application in industrial standard conditions, i.e. a powertrain running on a test bench. All these studies have demonstrated the suitability of the method in an industrial environment and illustrated the potential of the 3D reconstruction of parietal fields for the optimization of complex structures (discrimination and ranking of noise sources, correlation and coupling with numerical simulations...)
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Neuwirt, Christine [Verfasser]. "Acoustic Radiation Force Imaging der Schilddrüse: Generierung von Normwerten mittels Virtual TouchTM Imaging and Quantification / Christine Neuwirt." Ulm : Universität Ulm, 2017. http://d-nb.info/1129258483/34.
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Lawson, Mark Alan. "The acoustic aspects of visually impaired peoples' space : the lateralization of 3D sound in reverberant virtual environments." Thesis, University of Reading, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486324.
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This thesis is concerned with: Assessing the usefulness of spatial acoustics to navigation and testing the changing accuracy of that ability with changing stimuli, room acoustics and visual ability. The results of this study have the potential to inform good building and acoustic design, which could improve navigation, within buildings, for Visually Impaired People. This thesis describes the spatial hearing mechanism, termed .localisation or lateralization when using headphones and an experiment to test the effect of the hypothesised variables. These include sound stimuli type, room reverberation RT60 (2 • 0.5 second$) and visual impairment. The experiment. uses two sample groups of visually impaired persons (VIP) and non-visually impaired persons (NVIP). The results indicate that lateralization ability does not differ at a statistically significant level with visual ability; that lateralization using signals with strong Onset disparities is independent ofRT6O but not of Early Reflections; that lateralization using interaural level and timing differences is dependent on RT60 and; a person's subjective opinion of their ability or suitability of listening environment does not relate to objective performance. Lastly, it is hypothesised that: Onset Disparities constitute more reliable auditory information than ,. interaural level or timing differences and that they are thereby treated differently by the neurological system; That late reverberant energy will affect lateralization, only when there is an absence of strong directional cues and in these instances a subject's perception of a sound's direction may also be influenced by other factors such as, the direction of visual attention, and; That the ability of a subject to determine the direction of a sound by hearing is a function of training rather than visual ability.
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Ambróz, Richard. "Analysis of Powertrain Acoustic Properties." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-234137.
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Dizertačná práca rieši problematiku analýzy akustických vlastností pohonných jednotiek. V úvodnej časti je teoretický rozbor fyzikálnych princípov vibrácií a hluku a prehľad súčasného stavu riešenia problematiky v oblasti návrhu pohonných jednotiek. Vlastná časť práce popisuje konštrukčný návrh elektrodynamického budiča vibrácií, návrh hodnotenia výsledkov merania a taktiež spôsob spracovania výsledkov. Akustické vlastnosti sú hodnotené pomocou normálových rýchlostí kmitania povrchu. V závere práce sú prezentované ukážky využitia metódy v praktických príkladoch spojených s návrhom pohonnej jednotky. Celé riešenie predstavuje ucelený spôsob analýzy vhodný pre rýchle hodnotenie vplyvu konštrukčných úprav na akustické vlastnosti.
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Kestell, Colin D. "Active control of sound in a small single engine aircraft cabin with virtual error sensors." Title page, abstract and contents only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phk423.pdf.
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Low, Hwee Min Charles. "Computation of acoustic scattering from elastic conical shells with endcaps using the hybrid finite element/ virtual source approach." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/33421.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2004.Includes bibliographical references (p. 101-102).
Studying and understanding acoustic scattering pattern from underwater targets has been of interest to various communities such as the archeologists and the navy for several reasons and applications. The present state-of-the-art technique in this area involves such methods as analytical approach and FEM/BEM numerical technique. This thesis aims to study and demonstrate the power of using the hybrid virtual source/FE approach where the physical presence of a target is replaced by virtual sources placed in the vicinity of the target and in a manner where the pressure/displacement relationship on the target surface is satisfied by the virtual sources when the target is being insonified. Accurate results for the far-field radiation of the target can be obtained by superposition of the point source Green's function of each virtual source. The hybrid virtual source/FE approach shows potential to be a computationally efficient method for computing acoustic scattering. The derivation of the dynamic flexibility matrix for an elastic conical shell with endcaps will be illustrated in this thesis. It will be shown that the dynamic flexibility matrix corresponds to the acoustic admittance matrix in the virtual source approach where the scattering functions are computed in the MIT's program OASES/SCATT.
(cont.) Moreover, the benchmarking and validation of the approach will be conducted with the hybrid analytical/ virtual source approach. Firstly, the approach predicts natural frequencies close to the theoretical analysis for higher order modes with more than 2 circumferential transverse vibration lobes. Secondly, it produces displacement profile that conforms to analytical results. The scattering functions are also in agreement those computed by the hybrid analytical/ virtual source approach, with discrepancies observed at lower frequencies. In exact terms, discrepancies start to appear for frequency in the range of 1000 to 2000 Hz for a 0.01m thick, 2 m long, 0.3m radius steel cylinder without endcaps. The scattering functions will be compared with the SCATT/OASES virtual source approach for pressure release and rigid cylinders and cones. For the hybrid FE/virtual source approach, the structural sound speed and density approach zero and infinity for pressure-release and rigid target respectively. On the other hand, in the SCATT/OASES virtual source approach, the pressure and displacement are required to vanish on the target surface respectively. It will be shown that the two approaches agree with each other.
(cont.) Moreover, scattering functions over steel cones and cylinders for various frequencies have also been derived in this research. The results will be interpreted physically and theoretically in this thesis. The importance of including structural damping in the finite element formulation of the target so as to reflect the effect of resonance on scattering will be illustrated. Other issues, such as effect of target orientations on scattering, will also be investigated in this thesis. The code has shown good potential for adaptation to compute scattering over other axisymmteric shapes using conical shells and circular plates as building blocks and the hybrid FE/ virtual source approach.
by Hwee Min Charles Low.
S.M.