To effectively demonstrate the strength of using digital signal processing when producing sound effects, a sound effects demo is used at the lectures of the course TSRT78, Digital signal processing, which is given at the university in Linköping. The amount of effects, that in an instructive way can be used for an educational purpose, are many and the existing version of the sound effects demo is somewhat limited in its range of effects. This reports main focus lies in the presentation of what kind of effects which can be interesting in this kind of demo. All of the effects are presented with their background theory and examples on how they can be implemented in software, mainly with the focus on MATLABTM. Investigations on how well the effects can be run in realtime, in the toolbox SimulinkTM, has been made. In the report there is also a presentation of a new version of the sound effect demo that has been produced with user friendlieness and further updates in mind. In the new demo all of the effects are implemented, according to their presentations. The report finishes with suggestions for further work on the sound effects demo.

A reverberation chamber is a highly conductive cavity in which it is possible to generatehigh electromagnetic elds that can be considered statistically homogeneous. Reverberationchambers have existed as a resource for electromagnetic compatibility (EMC) testing formore than 30 years. Working to promote international co-operation on standardization, severalorganizations have published various EMC standards. At Combitech AB in Linkopinghave a chamber that is commercially used for dierent types of measurements. To makethe chamber more attractive and versatile it is within their interest to get a system whichis compatible with the latest standards. The project aimed to develop a control system forthe reverberation chamber at Combitech and to equip it with functionality enabling it tomake measurements according to current EMC standards. Using the programming softwareAgilent VEE a program was developed to communicate with the supporting equipment andmanage test routines. Within the program software lies functionality directly associate withmode stirring and mode tuning procedures for standards DO-160F and MIL-STD. Duringmeasurements the program has abilities for skipping frequencies, pause/continue the currentsweep, executing preset events and adding commented markers to the plot window. Someother usable functionality implemented is project save/load, help section, directory selectionand data export abilities. The system holds functionality enabling measurements accordingto the standards in question, though future work will be needed to be able to carry througha proper and correct measurement routine.

Die Elektromagnetische Verträglichkeit (EMV) betrachtet die Fähigkeit eines elektrischen Gerätes, in seiner elektromagnetischen Umgebung störungsfrei zu funktionieren, ohne diese dabei unzulässig zu stören. Zur Prüfung der Elektromagnetischen Verträglichkeit werden verschiedene Messumgebungen verwendet. Die Messung der strahlungsgebundenen Störfestigkeit und Störaussendung kann zum Beispiel in einer Modenverwirbelungskammer (MVK) erfolgen. Bei der Störfestigkeitsmessung wird der Prüfling einem externen Prüffeld ausgesetzt und untersucht, ob dieser die definierten Kriterien für einen störungsfreien Betrieb erfüllt. Für das Prüffeld muss vor der Messung nachgewiesen werden, dass die Anforderungen an dessen Homogenität eingehalten werden. Einen entscheidenden Einfluss auf die Homogenität des Prüffeldes hat der sogenannte Rührer. Bei einer MVK handelt es sich prinzipiell um einen Hohlraumresonator, in den ein mechanischer Rührer, d.h. ein elektrisch großer, drehbarer Streukörper integriert wird. Durch die Drehung des Rührers verändert sich die Feldverteilung in der MVK, was auch als Verwirbelung bezeichnet wird. Prinzipiell ergibt sich für jede Stellung des Rührers ein inhomogenes Feld mit lokalen Minima und Maxima. Ein Ziel bei der Verwendung von Modenverwirbelungskammern ist es, mit Hilfe geeigneter Verfahren Rührerstellungen zu finden, deren Feldverteilungen in Überlagerung ein möglichst homogenes Prüffeld erzeugen. Zum Lehrstuhl für Theoretische Elektrotechnik und Elektromagnetische Verträglichkeit der Technischen Universität Dresden gehört seit 2010 eine Modenverwirbelungskammer. Die Charakterisierung dieser MVK sowie eine weiterführende Untersuchung zur Wahl der Rührerstellungen bilden die Schwerpunkte der vorliegenden Arbeit. / In 2010 the Chair of Electromagnetic Theory and Compatibility of Technical University Dresden could extend its laboratories by a reverberation chamber with the dimensions 5.3 m, 3.7m and 3.0 m. Since then, a detailed characterisation of the chamber as well as further investigations have been the main emphasis of the authors research. The submitted doctoral thesis presents the obtained results. With the design, the fundamentals of operation and further characterisation of the reverberation chamber, given in Chapter 1 and 2, it aims to give an introduction and better understanding of reverberation chambers. On this basis, the authors research focused on methods for determining the independent stirrer positions in reverberations chambers. The results of the investigations are presented and summarised in chapter 3. One scope of Electromagnetic Compatibility are radiated immunity measurements. Besides the GTEM cell and the anechoic chamber the reverberation chamber gains in importance as an alternative measurement environment. A reverberation chamber is a shielded room with reflecting walls and one or more integrated mechanical stirrers. By rotating the stirrer the spatial boundary conditions for the electromagnetic field quantities are altered. The resulting change of the spatial field distribution depends on the location within the chamber and the geometry of the stirrer. Each stirrer position yields an inhomogeneous field distribution created by interfering waves. A general aim is to find a set of stirrer positions, whose superimposed field distributions create a more uniform test field. In practice, the given requirements for the homogeneity of the test field shall, with regards to an optimisation of measurement time, be realized with a minimum number of stirrer positions. In this context the term ’independent stirrer positions’ was established and describes stirrer positions, whose field distributions are linearly uncorrelated and therefore assumed to be practical for creating a more homogeneous test field using only a minimal number of stirrer positions. A general method for determining the number of independent stirrer positions in reverberation chambers is presented. The method uses a certain number of measurement positions in a defined test volume in order to characterize the spatial field distribution inside the chamber. Using the Pearson correlation coefficient the field distributions of the stirrer positions are tested for linear correlation and pairs of independent stirrer positions are determined. On this basis, cliques of pairwise independent stirrer positions are identified using appropriate algorithms. It is shown that the general method yields detailed information about the number and distribution of the independent stirrer positions and is therefore particularly suitable to evaluate other methods. Finally, the standard method according to IEC 61000-4-21 as well as selected alternative methods, that have been proposed in the past, are evaluated and compared based on the results of the general method.

Speech signals radiated in confined spaces are subject to reverberation due to reflections of surrounding walls and obstacles. Reverberation leads to severe degradation of speech intelligibility and can be prohibitive for applications where speech is digitally recorded, such as audio conferencing or hearing aids. Dereverberation of speech is therefore an important field in speech enhancement. Driven by consumer demand, blind speech dereverberation has become a popular field in the research community and has led to many interesting approaches in the literature. However, most existing methods are dictated by their underlying models and hence suffer from assumptions that constrain the approaches to specific subproblems of blind speech dereverberation. For example, many approaches limit the dereverberation to voiced speech sounds, leading to poor results for unvoiced speech. Few approaches tackle single-sensor blind speech dereverberation, and only a very limited subset allows for dereverberation of speech from moving speakers. Therefore, the aim of this dissertation is the development of a flexible and extendible framework for blind speech dereverberation accommodating different speech sound types, single- or multiple sensor as well as stationary and moving speakers. Bayesian methods benefit from – rather than being dictated by – appropriate model choices. Therefore, the problem of blind speech dereverberation is considered from a Bayesian perspective in this thesis. A generic sequential Monte Carlo approach accommodating a multitude of models for the speech production mechanism and room transfer function is consequently derived. In this approach both the anechoic source signal and reverberant channel are estimated using their optimal estimators by means of Rao-Blackwellisation of the state-space of unknown variables. The remaining model parameters are estimated using sequential importance resampling. The proposed approach is implemented for two different speech production models for stationary speakers, demonstrating substantial reduction in reverberation for both unvoiced and voiced speech sounds. Furthermore, the channel model is extended to facilitate blind dereverberation of speech from moving speakers. Due to the structure of measurement model, single- as well as multi-microphone processing is facilitated, accommodating physically constrained scenarios where only a single sensor can be used as well as allowing for the exploitation of spatial diversity in scenarios where the physical size of microphone arrays is of no concern. This dissertation is concluded with a survey of possible directions for future research, including the use of switching Markov source models, joint target tracking and enhancement, as well as an extension to subband processing for improved computational efficiency.

Wireless sensor network (WSN) has become a hot topic lately. By using WSN things that previously were difficult or impossible to measure has now become available. One of the main reasons using WSN for monitoring is to save money by cost optimization and/or increase safety by letting the user knowing the physical status of the monitored structure. This thesis considers four main topics, empirical testing of WSN in harsh environments, antenna designs, antenna measurements and radio environment emulation. The WSN has been tested in train environment for monitoring of ball bearings and inside jet engines to monitor strain of blades and temperatures. In total, two investigations have been performed aboard the train wagon and one in the jet engine. The trials have been successful and provide knowledge of the difficulties with practical WSN applications. The key issues for WSN are robust communication, energy management (including scavenging) and physical robustness. For the applications of WSN in harsh environments antennas has to be designed. In the thesis, two antennas has been designed, one for train environment and one for the receiver in the jet engine. In the train environment, a more isotropic radiation pattern is preferable; hence a small dual layered patch antenna is designed. The antenna is at the limit of being electrically small; hence slightly lower radiation efficiency is measured. For the WSN in the jet engine, a directive patch array is designed on an ultra-thin and flexible substrate. The thin substrate of the antenna causes rather lower radiation efficiency. But the antenna fulfils the requirements of being conformal and directive. In reverberation chambers are used to measure antennas, but there are difficulties to provide a realistic radio environment, for example outdoor or on-body. In this thesis, a large reverberation chamber is designed and verified. It enables measurement between 400 MHz and 3 GHz. Also, a sample selection method is designed to provide a post processing possibilities to emulate the radio environment inside the chamber. The method is to select samples from a data set that corresponds to a desired probability density function. The method presented in this thesis is extremely fast but the implementation of the method is left for future research. / WISENET / WiseJet

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Tomando os conhecimentos sobre o cérebro como mote organizador, esta tese buscou problematizar a intersecção entre o campo da ciência e o das artes. Para tanto, foi criada a ação artística “Reverberações do Corpo”, que objetivou a produção de uma obra de arte sobre o cérebro e representou um modo de articulação entre os campos do saber. Constituída como uma forma de arte política, envolvendo a participação do outro na confecção de uma obra sobre o cérebro, a ação foi composta pelos trabalhos artísticos produzidos durante a pesquisa e pelos artefatos culturais criados por profissionais de diferentes áreas acadêmicas. Os participantes foram convidados por meio de uma Carta-Convite, que teve origem a partir das problematizações acerca do cérebro e das criações artísticas da pesquisadora, geradas pela dissertação de mestrado, além de questionamentos sobre essa temática que circulam na cultura. A análise dos materiais considerou as reflexões provocadas pelos artefatos culturais e a perspectiva dos profissionais participantes, o encontro entre esses artefatos e a reverberação formada pelas suas reflexões, tanto em relação à produção artística da pesquisadora quanto às próprias análises que compõem a tese. Foram problematizados os discursos contemporâneos sobre o cérebro presentes nos artefatos criados, entre os quais se encontram os conhecimentos produzidos pelas descobertas da neurociência, que têm sido amplamente divulgados na mídia e que fazem parte do repertório cultural da população, a noção de que o cérebro define quem somos, os discursos sobre a plasticidade cerebral e o uso de imagens da neurociência em diferentes contextos, incluindo a compreensão da anatomia e funcionamento cerebral, o diagnóstico e tratamento de doenças, além de sua utilização em áreas híbridas, como o neuromarketing e a neuroeducação. O conceito de reverberação foi utilizado como forma de tensionamento da intersecção proposta nesta pesquisa, produzindo outro tipo de conhecimento, na fronteira entre a arte e a ciência. / Taking knowledge about the brain as an organizing motive, this thesis sought to discuss the intersection between the science and arts fields. For that purpose, an artistic action, "Reverberações do corpo" (Reverberations of the body), was created. It intended to produce a work of art about the brain and represented a connection between these two fields of knowledge. Conceived as a form of political art and comprising the engagement of the other in the making of a work about the brain, the action comprehended the artistic works presented throughout the research process and the cultural artefacts produced by professionals from different academic fields. Participants were brought on by means of an invitation letter originated from discussions about the brain and the researcher's own artistic creations which derive from her master's dissertation in addition to related topics that populate the cultural sphere. Assesment of the material took into account the reflections stirred by these cultural artefacts and the viewpoint of the participants, the meeting point of these artefacts and the reverberations caused by their reflection concerning the researcher's artistic production as well as the analyses within the thesis. We examine the contemporary discourses about the brain in these works. Those comprise knowledge produced by the new findings in neuroscience highly publicized in the media which are part of the general cultural repertoire, the notion that brain defines who we are, discourses about brain plasticity and usage of neuroscience images in various contexts including the comprehension of anatomy and brain function, diagnosis and treatment of diseases and also its usage in hybrid fields like neuromarketing and neuroeducation. The reverberation concept was used as a way of stretching and tightening the intersection proposed in this research work, generating another kind of knowledge, on the limits of art and science.

Tomando os conhecimentos sobre o cérebro como mote organizador, esta tese buscou problematizar a intersecção entre o campo da ciência e o das artes. Para tanto, foi criada a ação artística “Reverberações do Corpo”, que objetivou a produção de uma obra de arte sobre o cérebro e representou um modo de articulação entre os campos do saber. Constituída como uma forma de arte política, envolvendo a participação do outro na confecção de uma obra sobre o cérebro, a ação foi composta pelos trabalhos artísticos produzidos durante a pesquisa e pelos artefatos culturais criados por profissionais de diferentes áreas acadêmicas. Os participantes foram convidados por meio de uma Carta-Convite, que teve origem a partir das problematizações acerca do cérebro e das criações artísticas da pesquisadora, geradas pela dissertação de mestrado, além de questionamentos sobre essa temática que circulam na cultura. A análise dos materiais considerou as reflexões provocadas pelos artefatos culturais e a perspectiva dos profissionais participantes, o encontro entre esses artefatos e a reverberação formada pelas suas reflexões, tanto em relação à produção artística da pesquisadora quanto às próprias análises que compõem a tese. Foram problematizados os discursos contemporâneos sobre o cérebro presentes nos artefatos criados, entre os quais se encontram os conhecimentos produzidos pelas descobertas da neurociência, que têm sido amplamente divulgados na mídia e que fazem parte do repertório cultural da população, a noção de que o cérebro define quem somos, os discursos sobre a plasticidade cerebral e o uso de imagens da neurociência em diferentes contextos, incluindo a compreensão da anatomia e funcionamento cerebral, o diagnóstico e tratamento de doenças, além de sua utilização em áreas híbridas, como o neuromarketing e a neuroeducação. O conceito de reverberação foi utilizado como forma de tensionamento da intersecção proposta nesta pesquisa, produzindo outro tipo de conhecimento, na fronteira entre a arte e a ciência. / Taking knowledge about the brain as an organizing motive, this thesis sought to discuss the intersection between the science and arts fields. For that purpose, an artistic action, "Reverberações do corpo" (Reverberations of the body), was created. It intended to produce a work of art about the brain and represented a connection between these two fields of knowledge. Conceived as a form of political art and comprising the engagement of the other in the making of a work about the brain, the action comprehended the artistic works presented throughout the research process and the cultural artefacts produced by professionals from different academic fields. Participants were brought on by means of an invitation letter originated from discussions about the brain and the researcher's own artistic creations which derive from her master's dissertation in addition to related topics that populate the cultural sphere. Assesment of the material took into account the reflections stirred by these cultural artefacts and the viewpoint of the participants, the meeting point of these artefacts and the reverberations caused by their reflection concerning the researcher's artistic production as well as the analyses within the thesis. We examine the contemporary discourses about the brain in these works. Those comprise knowledge produced by the new findings in neuroscience highly publicized in the media which are part of the general cultural repertoire, the notion that brain defines who we are, discourses about brain plasticity and usage of neuroscience images in various contexts including the comprehension of anatomy and brain function, diagnosis and treatment of diseases and also its usage in hybrid fields like neuromarketing and neuroeducation. The reverberation concept was used as a way of stretching and tightening the intersection proposed in this research work, generating another kind of knowledge, on the limits of art and science.

Esta dissertação propõe uma reflexão no campo educacional sobre a formação docente numa perspectiva de coexistência de práticas pedagógicas que têm como referência a interação dialógica. A partir de minha pesquisa, abordo as reverberações que a formação docente pode produzir na prática do professor a partir de uma metodologia fundamentada na problematização do cotidiano e na invenção analisando o trabalho com sons realizado pelos alunos compondo a paisagem sonora da cidade imaginária. Esta proposta acolhe a coexistência de diferentes práticas e concepções existentes na escola propondo ao professor que realize experimentações a partir das reverberações que a formação docente instigar em sua prática cotidiana não desconsiderando sua trajetória e a rigidez dos currículos escolares. O cenário da pesquisa é uma turma de quarto ano de uma das professoras que integram o Projeto CIVITAS na zona rural, de uma Escola Municipal de Ensino Fundamental do Município de Sobradinho, Região Centro-Serra do RS. O projeto está vinculado ao LELIC – Laboratório de Estudos em Linguagem e Cognição do PPGEDU – Programa de Pós-graduação em Educação da UFRGS. A pesquisa está fundamentada na análise dialógica tendo como referência a teoria de Mikhail Bakhtin. A análise dialógica tem como pressuposto de pesquisa o respeito aos diferentes sujeitos que a compõe considerando-os como vozes importantes nos diálogos que se estabelecem entre o campo empírico e a teoria. Busco na teoria bakhtiniana os conceitos de dialogismo, relação dialógica, autoria, exotopia, produção de sentidos e entonação para realizar a análise dos registros além dos conceitos de paisagem sonora de Murray Schafer e escuta sensível de Barbier para pensar os sons como forma de linguagem e reverberação. A composição dos registros para análise se deu a partir dos enunciados produzidos pelos alunos, professora e pesquisadora em seus diários de bordo e interlocuções, nos registros de vídeo e fotografias colecionados pelos sujeitos da pesquisa. Nesta proposta de formação a professora torna-se pesquisadora a partir da problematização de sua prática e das interações dialógicas que estabelece produzindo sentidos que lhe possibilita mergulhar no universo da autoria. Os resultados da pesquisa nos permitem pensar que é possível a coexistência de diferentes práticas na escola a partir de uma proposta de formação docente, realizada em pequenos grupos buscando o diálogo entre os desafios cotidianos do professor e a teoria. A produção de sons para a cidade imaginária criada pelos alunos reafirma que a formação pode reverberar na sala de aula mediante diferentes experimentações e vivências quando o professor se permite uma prática que aceita situações inusitadas. / This work proposes a reflection about teacher education that utilizes a dialogic interaction approach mostly. From my research work, I explore reverberations that may be produced in teacher education practices utilizing a methodology based on problematisation of everyday life and on an invention that analyses sounds produced by the students. These sounds compose the soundscape of an imaginary city. This proposal embraces the coexistence of different school conceptions and practices which propose to the school teacher to carry out experiments emerging from reverberations that the teaching education instigates in its own practice not ignoring its history and the rigidity of school curricula. The study setting is a fourth year class whose teacher takes part in the CIVITAS project that takes place in a district school in a rural area in Sobradinho town, located in the Central-Mountain Region of RS. The project is linked to LELIC - Laboratory Studies in Language and Cognition of PPGEDU - Graduate Program in Education at UFRGS. The research is based on an analysis referenced to the dialogic theory of Mikhail Bakhtin. The dialogical analysis considers as its premise the research about its different subjects, regarding them as important voices in the dialogues that flourish between theory and the empirical field. I seek to study - in the Bakhtinian theory - the concepts of dialogism, dialogical relationship, authorship, outsidedness, production of meaning and intonation to examine records besides Murray Schafer’s soundscape and Barbier’s sensitive attention concepts to think sounds as language form and reverberation. The record composition to the analysis comes from utterances made by students, teacher and researcher in their logbooks and dialogues, video records and photographs collected by research subjects. In this proposed training the teacher becomes researcher from the questioning of their practice and the dialogic interactions, establishing meaning production that enables one to dive into the world of authorship. The survey results allow us to think that it is possible to attain the coexistence of different practices in the school from a teacher’s education proposal held in small groups seeking dialogue between the teacher's daily challenges and theory. The production of sounds for the imaginary town created by the pupils restate that the training may reverberate in the classroom through various trials and experiences when the teacher is allowed to propose pedagogical practices that accept unusual situations.

Combustion noise is central to several efforts to curb aircraft emissions. Indeed, acoustic waves originating in the combustor are a major contributor to aircraft noise. Moreover, they can act as a trigger for thermoacoustic instabilities, the consequences of which may range from decreased efficiency to outright failure. Modern engines designed to lower NOx emissions are particularly susceptible to this phenomenon. Unsteady combustion generates acoustic waves — direct noise — as well as convected flow disturbances, such as entropic, vortical or compositional inhomogeneities. These disturbances generate additional acoustic waves — indirect noise — if they are accelerated. The main objectives of this thesis are to examine the validity of current theoretical models for indirect noise, and to propose new ones where needed. First, a one-dimensional theoretical framework for the direct and indirect noise produced in a reflective environment is presented. The direct noise produced by the addition of mass, momentum and energy to a flow is determined analytically. A model for the entropic and compositional noise generated at a compact nozzle is then derived, accounting for nozzles with non-uniform entropy. Finally, the effect of reverberation (i.e. repeated acoustic reflections) is determined analytically. This enables direct and indirect acoustic sources to be identified and separated within experimental data, while eliminating the effect of acoustic reflections. The framework is applied to a model experiment — the Cambridge Wave Generator — in which direct, entropic and compositional noise are generated. Direct and indirect noise models are validated using experimental measurements of the sound field resulting from air injection and extraction, heat addition and helium injection. For the first time, direct, entropic and compositional noise are clearly identified in the experimental data, and shown to be in line with theoretical predictions. The results provide the first experimental demonstration of the compositional noise mechanism, and show that isentropic nozzle models are inadequate in predicting the indirect noise generated at nozzles with substantial losses.