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1

Anderson, Shaun David. "Time-frequency methods for the analysis of multistatic acoustic scattering of elastic shells in shallow water." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39640.

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The development of low-frequency sonar systems, using for instance a network of autonomous systems in unmanned vehicles, provides a practical means for bistatic measurements (i.e. when the source and receiver are widely separated) allowing for multiple viewpoints of the target of interest. Time-frequency analysis, in particular Wigner-Ville analysis, takes advantage of the evolution time dependent aspect of the echo spectrum to differentiate a man-made target (e.g. elastic spherical shell) from a natural one of the similar shape (e.g. solid). A key energetic feature of fluid loaded and thin spherical shell is the coincidence pattern, or mid-frequency enhancement echoes (MFE), that result from antisymmetric Lamb-waves propagating around the circumference of the shell. This thesis investigates numerically the bistatic variations of the MFE (with respect to the monostatic configuration) using the Wigner-Ville analysis. The observed time-frequency shifts of the MFE are modeled using a previously derived quantitative ray theory for spherical shell's scattering. Additionally, the advantage of an optimal array beamformer, based on joint time delays and frequency shifts (over a conventional time-delay beamformer) is illustrated for enhancing the detection of the MFE recorded across a bistatic receiver array.
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2

Bienvenu, Kirk Jr. "Underwater Acoustic Signal Analysis Toolkit." ScholarWorks@UNO, 2017. https://scholarworks.uno.edu/td/2398.

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This project started early in the summer of 2016 when it became evident there was a need for an effective and efficient signal analysis toolkit for the Littoral Acoustic Demonstration Center Gulf Ecological Monitoring and Modeling (LADC-GEMM) Research Consortium. LADC-GEMM collected underwater acoustic data in the northern Gulf of Mexico during the summer of 2015 using Environmental Acoustic Recording Systems (EARS) buoys. Much of the visualization of data was handled through short scripts and executed through terminal commands, each time requiring the data to be loaded into memory and parameters to be fed through arguments. The vision was to develop a graphical user interface (GUI) that would increase the productivity of manual signal analysis. It has been expanded to make several calculations autonomously for cataloging and meta data storage of whale clicks. Over the last year and a half, a working prototype has been developed with MathWorks matrix laboratory (MATLAB), an integrated development environment (IDE). The prototype is now very modular and can accept new tools relatively quickly when development is completed. The program has been named Banshee, as the mythical creatures are known to “wail”. This paper outlines the functionality of the GUI, explains the benefits of frequency analysis, the physical models that facilitate these analytics, and the mathematics performed to achieve these models.
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3

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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4

Davies, Jonathan James. "Underwater acoustic communications." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289679.

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5

Jenal, Ruztamreen Bin. "Fatigue crack detection using nonlinear acoustic : analysis of vibro-acoustic modulations." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531115.

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6

Locey, Lance Lester. "Analysis and Comparison of Three Acoustic Energy Density Probes." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd561.pdf.

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7

Sikström, Johannes. "Vibro-acoustic analysis of a satellite reflector antenna using FEM." Thesis, Umeå universitet, Institutionen för fysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-39875.

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The acoustic environment generated during launch is the most demanding structural load case for large, lightweight satellite reflector antennas. The reflector is exposed to extremely high sound pressure levels originating from the structural excitation of the rocket engines and exterior air flow turbulence. This thesis aims to predict the structural responses in the reflector due to the acoustic pressure load with a model based on Finite Element Modelling (FEM). The FE-model is validated against a previously performed Boundary Element Method (BEM) analysis. An approach called Split Loading together with a combination of BEM and FEM will be utilized to handle the surrounding air mass and the applied sound pressures. The idea of Split Loading is to divide the structure into several patches and apply a unit pressure load to each patch separately. In the last step the unit pressure is scaled and correlated by a power spectral density calculated from the acoustic pressures. Split Loading will be implemented in software packages MSC.NASTRAN/PATRAN. The model developed in this thesis handles both the added mass of the surrounding air and the sound pressure applied to the reflector. The model can qualitatively well reproduce the results of the BEM-analysis and the test data. However, the model tends to overestimate responses at low frequencies and underestimate them at high frequencies. The end results is that the model becomes too conservative at low frequencies to be used without further development.
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8

Pontén, Emeli. "Acoustic Design in Urban Development : analysis of urban soundscapes and acoustic ecology research in New York City." Thesis, Högskolan Dalarna, Ljud- och musikproduktion, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:du-4836.

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The world is urbanizing rapidly with more than half of the global population now living in cities. Improving urban environments for the well-being of the increasing number of urban citizens is becoming one of the most important challenges of the 21st century. Even though it is common that city planners have visions of a ’good urban milieu’, those visions are concerning visual aesthetics or practical matters. The qualitative perspective of sound, such as sonic diversity and acoustic ecology are neglected aspects in architectural design. Urban planners and politicians are therefore largely unaware of the importance of sounds for the intrinsic quality of a place. Whenever environmental acoustics is on the agenda, the topic is noise abatement or noise legislation – a quantitative attenuation of sounds. Some architects may involve acoustical aspects in their work but sound design or acoustic design has yet to develop to a distinct discipline and be incorporated in urban planning.My aim was to investigate to what extent the urban soundscape is likely to improve if modern architectural techniques merge with principles of acoustics. This is an important, yet unexplored, research area. My study explores and analyses the acoustical aspects in urban development and includes interviews with practitioners in the field of urban acoustics, situated in New York City. My conclusion is that to achieve a better understanding of the human living conditions in mega-cities, there is a need to include sonic components into the holistic sense of urban development.
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9

Brock, James L. "Acoustic classification using independent component analysis /." Link to online version, 2006. https://ritdml.rit.edu/dspace/handle/1850/2067.

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10

Teki, S. "Cognitive analysis of complex acoustic scenes." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1413017/.

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Natural auditory scenes consist of a rich variety of temporally overlapping sounds that originate from multiple sources and locations and are characterized by distinct acoustic features. It is an important biological task to analyze such complex scenes and extract sounds of interest. The thesis addresses this question, also known as the “cocktail party problem” by developing an approach based on analysis of a novel stochastic signal contrary to deterministic narrowband signals used in previous work. This low-level signal, known as the Stochastic Figure-Ground (SFG) stimulus captures the spectrotemporal complexity of natural sound scenes and enables parametric control of stimulus features. In a series of experiments based on this stimulus, I have investigated specific behavioural and neural correlates of human auditory figure-ground segregation. This thesis is presented in seven sections. Chapter 1 reviews key aspects of auditory processing and existing models of auditory segregation. Chapter 2 presents the principles of the techniques used including psychophysics, modeling, functional Magnetic Resonance Imaging (fMRI) and Magnetoencephalography (MEG). Experimental work is presented in the following chapters and covers figure-ground segregation behaviour (Chapter 3), modeling of the SFG stimulus based on a temporal coherence model of auditory perceptual organization (Chapter 4), analysis of brain activity related to detection of salient targets in the SFG stimulus using fMRI (Chapter 5), and MEG respectively (Chapter 6). Finally, Chapter 7 concludes with a general discussion of the results and future directions for research. Overall, this body of work emphasizes the use of stochastic signals for auditory scene analysis and demonstrates an automatic, highly robust segregation mechanism in the auditory system that is sensitive to temporal correlations across frequency channels.
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11

Hiller, Steven Mark. "Automatic acoustic analysis of waveform perturbations." Thesis, University of Edinburgh, 1985. http://hdl.handle.net/1842/18962.

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12

Vogel, Ryan N. "Structural-Acoustic Analysis and Optimization of Embedded Exhaust-Washed Structures." Wright State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=wright1374833633.

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13

Shen, Chia-Hsuan. "Acoustic Based Condition Monitoring." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1341797408.

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14

Heckl, Maria Anna. "Heat sources in acoustic resonators." Thesis, University of Cambridge, 1985. https://www.repository.cam.ac.uk/handle/1810/250863.

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15

Mathiyaparanam, Jeyisanker. "Analysis of acoustic emission in cohesionless soil." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001715.

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16

Miller, Teresa S. "Turbulent boundary layer models for acoustic analysis." Diss., Wichita State University, 2011. http://hdl.handle.net/10057/3933.

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An analysis of the three types of turbulent boundary layer (TBL) models for acoustic analysis is presented because current preferred models over-predict TBL contributions to aircraft interior noise predictions. The mean square pressure is a measure of the total energy due to the pressure fluctuations beneath a turbulent boundary layer. The single point wall pressure spectrum sorts the energy into frequencies. The normalized wavenumber-frequency spectrum sorts the energy into wavenumbers. The pressure fluctuations beneath a turbulent boundary layer are found by solving the Poisson equation. In this work, the Poisson equation is solved both numerically and analytically using data from an LES/DES simulation. The numerical solution uses the point Gauss-Seidel method and has reasonable results. The analytical solution uses an eigenvalue expansion method that is less successful. The empirical mean square pressure models predict a relatively large spread in the pressure fluctuation values. It is difficult to draw any meaningful conclusions on which mean square pressure model is preferred when compared to data from the Spirit AeroSystems 6x6 duct. The single point wall pressure spectrum models are evaluated and the two more modern models of Smol’yakov and Goody seem to perform the best. These models are also compared to data from the Spirit AeroSystems 6x6 duct. The spectrum at low frequencies rolled off similar to the Goody model. This analysis indicates that the Goody model is the appropriate single point wall pressure spectrum model for aircraft applications. Important features of the normalized wavenumber-frequency spectrum models are presented and can be classified as either separable or non-separable. Separable models in the Corcos normalized wavenumber-frequency spectrum model class tend to over-predict the response for a range of cases. Both the non-separable Chase 1 and Smol’yakov-Tkachenko models appear to match the M.I.T. low noise, low turbulence wind tunnel data throughout the range of comparison. The Smol’yakov-Tkachenko model does not lend itself to straight forward Fourier transforms needed by the acoustic models. But the Chase 1 model can be converted from wavenumber-frequency spectrum to the cross spectrum, so it is the preferred model for aircraft applications. Therefore, the preferred turbulent boundary layer models for aircraft interior noise predictions are the single point wall pressure spectrum model of Goody and the normalized wavenumber-frequency spectrum model of Chase 1.
Dissertation (Ph.D.)--Wichita State University, College of Engineering, Dept. of Aerospace Engineering
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17

Elfergani, Hisham. "Acoustic emission analysis of prestressed concrete structures." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/49383/.

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This thesis examines the role of Acoustic Emission (AE) as a non-destructive testing (NDT) technique for prestressed and reinforced concrete structures. The work focuses on the development of experimental techniques and data analysis methods for the detection, location and assessment of AE from prestressed and reinforced concrete specimens. This thesis reveals that AE can be used to detect the onset of corrosion activity in wire in the interface between prestressed concrete and mortar as found in prestressed concrete pipes. Furthermore, this technique can be used to locate the corrosion activity on different size prestressed concrete samples. By correlation between three parameters of classical AE analysis techniques (traditional parameters), damage can be detected and located whilst the corrosion area, macro crack and crack propagation can be identified. However, it cannot classify the crack type. Different damage modes, including corrosion activity, micro/macro cracking formation, crack propagation and wire failure generate different types of AE signals with varying amplitudes and absolute energy emitted. A novel analysis approach has been used on composite materials (concrete, mortar and steel) to evaluate differing crack types by a combination of the classical acoustic emission analysis technique and advanced analysis Rise time / Amplitude (RA) and Average Frequency (AF), results proved the effectiveness of the developed techniques for damage detection and classification crack types. The relationship between RA value and AF value can be used to determine the crack area and classify it as either tensile crack type, other type (shear movement) or no crack. The results of the research have demonstrated that the AE technique is valid in larger scale monitoring and hence the potential for monitoring real structures such as prestressed concrete pipes. Use of Kernel Density Estimation Function (KDEF) provides improved visualisation of the data to represent clearly the RA/AF values. Key Words: Acoustic Emission, Corrosion, Reinforced Concrete, Prestressed Concrete, Micro and Macro Concrete Cracks, Crack classification, Source Location, Damage Assessment, Monitoring.
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18

Yi, Gina Ann. "A software toolkit for acoustic respiratory analysis." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/33391.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.
Includes bibliographical references (p. 143-147).
Millions of Americans suffer from pulmonary diseases. According to recent statistics, approximately 17 million people suffer from asthma, 16.4 million from chronic obstructive pulmonary disease, 12 million from sleep apnea, and 1.3 million from pneumonia - not to mention the prevalence of many other diseases associated with the lungs. Annually, the mortality attributed to pulmonary diseases exceeds 150,000. Clinical signs of most pulmonary diseases include irregular breathing patterns, the presence of abnormal breath sounds such as wheezes and crackles, and the absence of breathing entirely. Throughout the history of medicine, physicians have always listened for such sounds at the chest wall (or over the trachea) during patient examinations to diagnose pulmonary diseases - a procedure also known as auscultation. Recent advancements in computer technology have made it possible to record, store, and digitally process breath sounds for further analysis. Although automated techniques for lung sound analysis have not been widely employed in the medical field, there has been a growing interest among researchers to use technology to understand the subtler characteristics of lung sounds and their potential correlations with physiological conditions. Based on such correlations, algorithms and tools can be developed to serve as diagnostic aids in both the clinical and non-clinical settings.
(cont.) We developed a software toolkit, using MATLAB, to objectively characterize lung sounds. The toolkit includes a respiration detector, respiratory rate detector, respiratory phase onset detector, respiratory phase classifier, crackle and wheeze detectors and characterizers, and a time-scale signal expander. This document provides background on lung sounds, describes and evaluates our analysis techniques, and compares our work to approaches in other diagnostic tools.
by Gina Ann Yi.
M.Eng.
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19

Richardson, Philip. "Acoustic analysis and tuning of cylindrical membranophones." Thesis, Anglia Ruskin University, 2010. http://arro.anglia.ac.uk/189010/.

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This thesis scientifically investigates the setup and tuning of cylindrical membranophones as musical instruments. To date there has been very little quantitative analysis of drum tuning with respect to performance sound, studio recording and music production. Digital signal analysis has been used to quantify a number of acoustic related factors to drum setup and tuning. This is concerned with the evaluation of a drum's free vibration once excitation has occurred. Novel analysis of membranophone response is performed with respect to tuning an 'equalised drumhead'. Such analysis has not previously been performed on cylindrical drums with two heads. The findings show that it is indeed possible to tune a drum to a chosen, uniform frequency response and to a quantified accuracy. With reference to previous, non-scientific literature, the fundamental frequency of each drum in the modern drum kit is shown for the first time to be objectively tunable to correspond to a musical pitch. The research also investigates the role of the resonant head in tuning cylindrical drums. Unique analysis of the interaction between the two membranes shows for the first time that the ratios of the modal frequencies present in a drum sound are not fixed and can be manipulated to more desirable ratios. The fundamental frequently present is shown to be the same for both batter and resonant heads due to the strong coupling effect of the (01) modes. Furthermore the current research shows how this ability to manipulate the frequencies present in the drum can be extended to the drum kit as a whole and how the envelope profile of cylindrical drums with two heads can be manipulated via tuning and damping. This research therefore provides an original contribution to the knowledge of drum tuning for both scientific and musical purposes.
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Hansen, Joseph T. "Link budget analysis for undersea acoustic signaling." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FHansen.pdf.

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21

Einstein, Daniel Richard. "Nonlinear acoustic analysis of the mitral valve /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/8064.

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22

Nicholson, Guy Charles. "The active control of acoustic impedance." Thesis, University of Salford, 1994. http://usir.salford.ac.uk/14778/.

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The application of an active control force on a thin-walled acoustic boundary can modify the motional dynamics, and so influence the impedance presented to incident waves. This impedance determines transmission of acoustic energy, reflection of acoustic waves from the boundary and absorption of incident energy. This thesis studies control systems that generate control forces for the active control of surface acoustic impedance. The proposed systems rely on measurement of the acoustic pressure and surface velocity of the boundary. The systems can use adaptive digital signal processing, which offers significant advantages over non-adaptive techniques. The active control of the specific acoustic impedance of a loudspeaker that terminates a waveguide for axially propagating plane waves provides a motivating problem. Theoretical analysis establishes the control of specific acoustic impedance of a simple compliantly-suspended piston by a control force. Operational constraints of a physical piston define theoretical operating limits for controlled specific acoustic impedances. The control systems use either feedback or feed-forward techniques for which theoretical treatment reveals restrictions on the range of controlled specific acoustic impedance. A novel result is that conventional implementations of the control systems can be unstable for certain desired impedances unless feedback cancellation is used. Digital feedback techniques are less effective for broader frequency bandwidth where feed-forward techniques may work. Theoretical analysis produces solutions that confirm the feasibility of these control techniques for the active control of specific acoustic impedance. Potential errors in the implementation of the systems have predictable effects on the controlled specific acoustic impedance. Experimental results support the theoretical work presented in this thesis, demonstrating active control of specific acoustic impedance for normally incident acoustic plane waves. An adaptive digital feed-forward control system creates desired specific acoustic impedances for band-limited noise and transient signals.
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23

Uzoegbo, Herbert Chidozie. "Propagation of acoustic waves in concrete." Thesis, King's College London (University of London), 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321500.

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Harvey, Alan Paul. "Nonlinear surface acoustic waves and applications." Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.255827.

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25

Xu, Buye. "Generalized Acoustic Energy Density and Its Applications." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2339.

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The properties of acoustic kinetic energy density and total energy density of sound fields in lightly damped enclosures have been explored thoroughly in the literature. Their increased spatial uniformity makes them more favorable measurement quantities for various applications than acoustic potential energy density (or squared pressure), which is most often used. In this dissertation, a new acoustic energy quantity, the generalized acoustic energy density (GED), will be introduced. It is defined by introducing weighting factors, α and 1 − α, in the formulation of total acoustic energy density. With the additional degree of freedom, the GED can conform to the traditional acoustic energy density quantities, or be optimized for different applications. The properties and applications of the GED are explored in this dissertation. For enclosed sound fields, it was found that GED with α = 1/4 is spatially more uniform than the acoustic potential energy density, acoustic kinetic energy density, and the total acoustic energy density, which makes it a more favorable measurement quantity than those traditional acoustic energy density quantities for many indoor measurement applications. For some other applications, such as active noise control in diffuse field, different values of α may be considered superior. The numerical verifications in this research are mainly based on a hybrid modal expansion developed for this work, which combines the free field Green's function and a modal expansion. The enclosed sound field is separated into the direct field and reverberant field, which have been treated together in traditional modal analysis. Studies on a point source in rectangular enclosures show that the hybrid modal expansion converges notably faster than the traditional modal expansions, especially in the region near the source, and introduces much smaller errors with a limited number of modes. The hybrid modal expansion can be easily applied to complex sound sources if the free field responses of the sources are known. Damped boundaries are also considered in this dissertation, and a set of modified modal functions is introduced, which is shown to be suitable for many damped boundary conditions.
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Nulsen, Susan, and n/a. "Combining acoustic analysis and phonotactic analysis to improve automatic speech recognition." University of Canberra. Information Sciences & Engineering, 1998. http://erl.canberra.edu.au./public/adt-AUC20060825.131042.

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This thesis addresses the problem of automatic speech recognition, specifically, how to transform an acoustic waveform into a string of words or phonemes. A preliminary chapter gives linguistic information potentially useful in automatic speech recognition. This is followed by a description of the Wave Analysis Laboratory (WAL), a rule-based system which detects features in speech and was designed as the acoustic front end of a speech recognition system. Temporal reasoning as used in WAL rules is examined. The use of WAL in recognizing one particular class of speech sounds, the nasal consonants, is described in detail. The remainder of the thesis looks at the statistical analysis of samples of spontaneous speech. An orthographic transcription of a large sample of spontaneous speech is automatically translated into phonemes. Tables of the frequencies of word initial and word final phoneme clusters are constructed to illustrate some of the phonotactic constraints of the language. Statistical data is used to assign phonemes to phonotactic classes. These classes are unlike the acoustic classes, although there is a general distinction between the vowels, the consonants and the word boundary. A way of measuring the phonetic balance of a sample of speech is described. This can be used as a means of ranking potential test samples in terms of how well they represent the language. A phoneme n-gram model is used to measure the entropy of the language. The broad acoustic encoding output from WAL is used with this language model to reconstruct a small test sample. "Branching" a simpler alternative to perplexity is introduced and found to give similar results to perplexity. Finally, the drop in branching is calculated as knowledge of various sets of acoustic classes is considered. In the work described in this thesis the main contributions made to automatic speech recognition and the study of speech are in the development of the Wave Analysis Laboratory and in the analysis of speech from a phonotactic point of view. The phoneme cluster frequencies provide new information on spoken language, as do the phonotactic classes. The measures of phonetic balance and branching provide additional tools for use in the development of speech recognition systems.
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Sarikaya, Tevfik Bahadir. "A Comparative Analysis Of Matched Field Processors For Underwater Acoustic Source Localization." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612578/index.pdf.

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In this thesis, localization of the underwater sound sources using matched field processing technique is considered. Localization of the underwater sound sources is one of the most important problems encountered in underwater acoustics and signal processing. Many techniques were developed to localize sources in range, depth and bearing angle. However, most of these techniques do not consider or only slightly takes into account the environmental factors that dramatically effect the propagation of underwater sound. Matched field processing has been developed as a technique that fully considers the environmental factors. Matched field processing has proven to be successful in many applications such as localization of sources in range and depth, the determination of environmental parameters, and the evaluation of model accuracies. In this study, first a comparative analysis of narrowband matched field processors is given. Namely four main processors: Bartlett processor, Minimum Variance Distortionless Response (MVDR) processor, MVDR with neighboring location constraints and MVDR with environmental perturbation constraints are compared in terms of their probability of correct localization under certain environmental conditions. Secondly, a performance assesment for the most common broadband matched field processors is made. The correct localization performances for incoherent broadband matched field processor, Tolstoy/Michalopoulo'
s coherent matched field processor and broadband matched field processor with environmental perturbation constraints is given for certain environmental conditions. Finally, a new weighting approach to combine data for broadband matched field processing is introduced. The fact that information from different frequencies may have different reliability depending on the environmental conditions is considered to develop a weighting scheme. It is shown that a performance gain compared to existing processors can be achieved by using the weighting scheme introduced in this study.
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John, Jeeva. "Acoustic Analysis of Speech of Persons with Autistic Spectrum Disorders." Bowling Green State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1206329066.

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Tashmukhambetov, Arslan. "Experimental Design, Data Analysis, and Modeling for Characterizing the Three-Dimensional Acoustic Field of a Seismic Airgun Array." ScholarWorks@UNO, 2009. http://scholarworks.uno.edu/td/1084.

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In June 2003, the Littoral Acoustic Demonstration Center conducted an acoustic characterization experiment for a standard seismic exploration array. Two moorings with Environmental Acoustic Recording Systems (EARS) were deployed in the northern part of the Gulf of Mexico to measure ambient noise and collect shot information. A 21-element seismic airgun array was towed along five parallel linear tracks with horizontal closest approach points to the EARS buoy position of 63, 500, 1000, 2000, and 5000 m. Calibrated acoustic pressure measurements collected during the experiment were analyzed to obtain zero-to-peak sound pressures, sound exposure levels, and pressure levels in 1/3-octave frequency bands. In addition, the experimental data were modeled by using a modified underwater acoustic propagation model to fill in missing data measurements. The resulting modeling procedure showed good agreement between measured and modeled data in absolute pressure amplitudes and frequency interference patterns for frequencies up to 1000 Hz. The analysis is important for investigating the potential impact on marine mammals and fish and predicting the exposure levels for newly planned seismic surveys in other geographic areas. Based on results of the experiment conducted and data analysis performed, a new experimental design was proposed to maximize the amount of collected data using the available equipment while minimizing the time needed for the source ship. The design used three patches, one with 3º angular spacing between the lines at a reference depth. Embedded is a smaller patch with 1º spacing and within that a still smaller patch with one half degree spacing. This arrangement gives a reasonably uniform distribution of shots versus solid angle with a large variety of emission and azimuthal angles for different ranges. Due to the uncertainty of positioning systems, the angular space is divided into solid angle bins. Simulations predicted more than 200 shots per bin for emission angles greater than 13 degrees. Statistical analysis of collected data will be performed on the proposed bin basis. An experiment based on the proposed design was conducted in Fall 2007. The data measurements collected during the experiment are currently being analyzed and will be reported in the near future.
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Wang, Chong Aerospace &amp Mechanical Engineering Australian Defence Force Academy UNSW. "Vibro-acoustic analysis of inverter driven induction motors." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Aerospace and Mechanical Engineering, 1998. http://handle.unsw.edu.au/1959.4/38706.

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With the advent of power electronics, inverter-driven induction motor are finding increased use in industries because of applications that demand variable speed operations and because of the potential savings in energy usage. However, these drives sometimes produce unacceptably high levels in vibration and acoustic noise. A literature survey has revealed that while there has been intensive research on the design of inverters to minimize acoustic noise radiation from these drives, the vibro-acoustic behaviour of an induction motor structure has received relatively little attention. The primary objective of this research project, therefore, is to develop a general strategy/algorithm for estimating the acoustic noise radiated from inverter-driven induction motors. By using a three-phase, 2.2 kW induction motor, the vibration modes due to various structural components (such as the rotor, the stator/casing, the endshields and the base plate) of the motor structure were analysed by experimental modal testing. Results indicate that the vibration modes due to the rotor are only important at low frequencies. It has been found that the power injection method gives more accurate measurement of the damping of a motor structure than the modal testing and the time decay methods. If a point force excitation is used, then it is more accurate to measure the sound radiation efficiency than the power conversion efficiency for motor structures. The effect of three different inverter designs (an ideal ???almost sinusoidal??? controller and two commercially available PWM inverters) on the radiated acoustic power were assessed for both no-load and load conditions using sound intensity measurements conducted in an anechoic room. The results indicate that although the sound power level due to aerodynamic and mechanical noise increases at a rate of 12 dB per doubling of the motor speed, the electromagnetic noise dominates at low motor speeds and is still a significant noise source even at high motor speeds. For inverters with low switching frequencies, the radiated sound power level is almost 15 dB higher than the ideal case at low speeds and is relatively insensitive to the motor speed. For inverters that implement the random modulation technique, the change in the total sound power level with the level of the random modulation is very small but the tonal nature of the noise is greatly reduced. The vibration behaviour of a motor structure was modeled using the finite element method (FEM) and validated using the experimental modal testing results. It has been found that it is essential to model the laminated stator as an orthotropic structure. While the details of other structural components (such as the endshields, the teeth in the stator and the windings) are not so important, it is essential that they are incorporated into the structural model as simplified structures to account for their mass, stiffness and boundary conditions imposed on the motor structure. Based on this structural model, the radiated acoustic power for various operating conditions has been predicated using the boundary element (BEM) and the electromagnetic force calculated from an electromagnetic finite element model. The predicted results agree reasonably well with experimental measurements. Despite the success of the FEM/BEM approaches, they can be prohibitively expensive (in terms of computer resources required) to apply to large motors and high frequencies. Thus the feasibility of using a statistical method, namely, the statistical energy analysis (SEA), to estimate the radiated acoustic sound power from an inverter-driven induction motor has been examined. In order to carry out this analysis, analytical expressions for calculating the natural frequencies and radiation efficiency of finite length circular cylindrical shells (which are simplified models of the stator and casing of a motor structure) were firstly derived. The internal loss factors and coupling loss factors of the motor structure were determined experimentally using the power injection method. Then by introducing an equivalent surface mobility of circular cylindrical shells for the electromagnetic force, the vibration response and the acoustic noise radiated from each part of the motor structure were estimated. Results indicate that SEA method is potentially an efficient and effective tool in estimating the noise radiated from inverter-driven induction motors.
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31

Jeans, Richard. "Innovative methods for three dimensional fluid-structure interaction." Thesis, Imperial College London, 1992. http://hdl.handle.net/10044/1/8189.

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32

Ali, Andreas Mantik. "Distributed acoustic localization and tracking design and analysis." Diss., Restricted to subscribing institutions, 2010. http://proquest.umi.com/pqdweb?did=2023768071&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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33

Yildirim, Baran. "Acoustic Wave Analysis Using Different Wave Propagation Models." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609527/index.pdf.

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In this study in order to simulate the acoustic waves, Ray Theory and Normal Mode models are used. These methods are analyzed using MATLAB simulation tool
differences between two models are examined and a region with a known bottom profile and sound velocity profiles is investigated. The Ray Theory is used in acoustic systems which is the one of the applications of wave modeling. Ray theory is solved with standard Ordinary Differential Equation solvers and normal mode with finite element method. Different bottom profiles and sound velocity profiles previously taken are interpolated to form an environment and examined in the case study. in the case study.
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34

Kudo, Hiroaki, Jinji Chen, and Noboru Ohnishi. "Scene Analysis by Clues from the Acoustic Signals." INTELLIGENT MEDIA INTEGRATION NAGOYA UNIVERSITY / COE, 2004. http://hdl.handle.net/2237/10426.

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35

Brown, Timothy J. "Experimental analysis of acoustic adaptation in bird song." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq31092.pdf.

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36

Philips, Scott M. "Perceptually-driven signal analysis for acoustic event classification /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/5934.

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37

Cicirello, Alice. "Vibro-acoustic analysis of structures with uncertain properties." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608078.

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38

Jones, Catherine Jacquelynn Julia. "Queclaratives in Xhosa : an acoustic and perceptual analysis." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52426.

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Thesis (PhD)--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: Key words: acoustic speech analysis, speech synthesis, speech perception, copulative queclarative, linguistics, psycho linguistics, human language technology This study investigates the notion of interrogativity in Xhosa as expressed in the form of Queclaratives. Queclaratives, or statements which are question-like in function, have been studied in many languages of the world. Unfortunately with regard to the Bantu languages, studies relating to interrogativity in general have largely been impressionistic in nature. This research comprised two aspects of analysis. These included an acoustic and a perceptual analysis of data. The reason for this approach is that, without this combination the results could have been considered to be suspect and lacking in authenticity. The acoustic analysis was conducted on 858 words in statement and queclarative pairs. Significant parameters were extracted and these were then statistically analyzed. The results revealed that duration on the penultimate vowel, pitch on the penultimate vowel and the overall raised pitch of queclaratives as opposed to statements were indeed the acoustically significant parameters differentiating statements from queclaratives. However as is well known, there is no one-to-one relationship between the acoustic signal and its perception and, therefore, it is imperative that such findings also be perceptually tested. The perceptual testing of these parameters was conducted in an attempt to elicit whether they were perceptually significant and also at what point in the utterance listeners could differentiate between queclaratives and statements. The next progression was the compilation of carefully designed perception tests on the acoustically significant parameters. Two experiments were compiled using stimuli that were manipulations of the original signal of one of the selected informant's utterances. These tests were administered on multimedia computers in the Language Laboratory at the University of Stellenbosch using 64 subjects for the first experiment and 63 for the second. The results of the perception tests showed that duration and pitch on the penultimate syllable are perceptually highly significant in differentiating statements from queclaratives. However the results also indicated very early recognition of the different forms with minimal speech segments from which the penultimate vowels were absent altogether. This then suggests that the perceptual judgements made earlier in the utterance may be either reinforced or overridden by the duration and pitch on the penultimate vowel. These results have assisted in the validation of some impressionistic claims made within the Bantu and other languages, while refuting others. However, as this corpus of data has included research on copulative queclaratives, it appeals for further research on this subject using any other linguistic markers. The results have also been evaluated in terms of their possible contribution to the related disciplines of psycholinguistics, linguistics and human language technologies. In so doing, the thesis makes an urgent appeal to researchers to pursue this experimental approach to language research. Another appeal is made for an awareness campaign as to the importance of this approach in harnessing the power of language for the development of language and society as a whole. The fertility of the South African society lies in its richness of multilingualism and the necessity for the improvement of the dissemination of information to all people of all languages and the improvement of communication between people in general, including those less fortunate in terms of literacy skills.
AFRIKAANSE OPSOMMING: Sleutelwoorde: akoestiese spraakanalise, spraaksintese, spraakpersepsie, kopulatiewe stelvraag, linguistiek, psigolinguistiek, taal-en-spraaktegnologie In hierdie projek word die aard van vraagstelling in Xhosa ondersoek met betrekking tot die stelvraag-vorm. Stelvrae, of stellings wat ook as vrae kan funksioneer, is reeds bestudeer vir heelwat wêreldtale. Oor die algemeen was studies oor vraagstelling in die Afrikatale egter grootliks impressionisties van aard. Hierdie navorsingsprojek het uit twee analisekomponente bestaan, naamlik 'n akoestiese analise van die data en 'n reeks persepsueie eksperimente. Sonder die kombinasie van die twee tipes analise sou die resultate van die navorsing minder kredietwaardig gewees het. Die akoestiese analise is gedoen op 858 woordpare bestaande uit stellings en stelvrae. Die data is statisties ontleed en die relevante parameters is onttrek. Die resultate het daarop gedui dat die duur en toonhoogte van die voorlaaste vokaal sowel as die register van die hele woord belangrike parameters is in die onderskeid tussen stellings en stelvrae. Aangesien dit wel bekend is dat daar nie 'n een-tot-een verwantskap tussen die akoestiese klanksein en die persepsie daarvan is nie, is dit noodsaaklik om ook 'n persepsueie eksperiment uit te voer. Die persepsueie toetse is so opgestel dat bepaal kon word watter akoestiese parameters ook persepsueel relevant is en om die vroegste sillabie te vind waar luisteraars reeds die onderskeid tussen die twee vorme kan maak. Die volgende stap was om stimuli vir die persepsietoetse op te stel wat inderdaad bogenoemde resultate sou lewer. Stimuli is geskep deur die spraakdata van een spreker te manipuleer. Die persepsietoetse is toe uitgevoer op multimedia-rekenaars in die Taallaboratorium van die Universiteit van Stellenbosch. Die resultate van die persepsietoetse het gewys dat die duur en toonhoogte van die voorlaaste sillabe ook persepsueel belangrik is in die ondersekeid tussen die verskillende vorme. Dit was ook duidelik dat proefpersone die vorme van mekaar kon onderskei met minimale hoeveelhede inligting waar die voorlaaste en laaste sillabes heeltemal afwesig was. Dit dui daarop dat luisteraars persepsuele besluite baie vroeg in die woord neem, maar dat hierdie besluite óf versterk óf omgekeer kan word deur die duur en toonhoogte van die voorlaaste sillabe. Die resultate van die navorsing het sekere impressionistiese stellings ten opsigte van Afrikatale ondersteun terwyl ander stellings as foutief bewys is. Een van die belangrike bevindings was dat die impressionistiese standpunt dat stellings 'n dalende intonasiekontoer en vrae 'n stygende intonasiekontoer tydens die afloop van die uiting het, 'n oorvereenvondiging is. Hierdie werk is gedoen op enkelwoord-kopulatief stelvrae en leen dit daartoe om uitgebrei te word na frases en sinne vir toekomstige navorsmg. Verder is die navorsingsresultate in verband gebring met verwante dissiplines soos psigolinguistiek, linguistiek en taal- en spraaktegnologie. 'n Pleidooi is gelewer vir 'n bewusmakingsveldtog om die belangrikheid van hierdie tipe navorsing te beklemtoon om die potensiaal van taal te benut vir die ontwikkeling van Suider-Afrikaanse tale en gemeenskappe. Die rykheid van ons gemeenskap lê in die veeltaligheid daarvan en bied besondere uitdagings om die verspreiding van inligting na alle mense van alle tale te verbeter en om die kommunikasie tussen mense in die algemeen, maar ook spesifiek vir diegene met laer vlakke van geletterdheid.
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39

Miller, D. G. "Acoustic emission analysis of an automotive paint system." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/47293.

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40

Hara, Isao. "An acoustic analysis of vowel sequences in Japanese." Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3420.

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For many years, researchers on phonetics have been trying to characterise a sound of languages from various points of view and employing a variety of approaches and methods. Some researchers have focused on finding some common features across languages while others have concentrated on the phonetic details of a particular language. This thesis aims to investigate, using acoustic analysis methods, the properties of non-identical vowel sequences of a particular language, Japanese, thereby enhancing our knowledge of the phonetic characteristics of this particular language and in the process shedding light on phonetic categories which are routinely used across languages.
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41

Mleczko, Michał [Verfasser]. "Acoustic Analysis of Ultrasound Contrast Agents / Michał Mleczko." München : Verlag Dr. Hut, 2011. http://d-nb.info/1013526015/34.

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42

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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43

Rae, George J. "Flow induced acoustic resonances in heat exchangers." Thesis, Robert Gordon University, 1986. http://hdl.handle.net/10059/608.

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This thesis describes an investigation into the acoustic phenomenon in in-line tubular heat exchangers subjected to cross flow. The flow through such a heat exchanger can result in the production of very high noise levels, which occur as a result of the excitation of an acoustic standing wave in the cavity between the tube rows. This acoustic vibration can occur in large and small heat exchangers alike, resulting in drastically impared performance and working life. The phenomenon associated with such vibration is poorly understood and considerable anomalies still exist in published literature. There are several theories which attempt to describe this mechanism, however, none of these can satisfactorily account for its complex nature. The objective of the present work was to carry out an investigation to assess this acoustic phenomenon. The initial stages of this work produced an experimental rig to allow the phenomenon to be fully investigated, this included the examination of the effect of row depth and bank geometry on the acoustic resonance. The next step was to determine the role played by acoustic damping. This included making measurements of the damping under flow conditions and establishing its dependancy on velocity. A method of increasing the acoustic damping of a given bank was developed and incorporated in a tube bank. The results obtained from these experiments revealed that the acoustic system behaved in a manner which was consistent with that of a self excited system. Finally an appropriate mathematical model of the system was developed. The model,, which considers an acoustic feedback effect, was found to give quite an accurate representation of the system, and has the ability to account for all the observations made in this investiagation. This, together with the experimental results, enabled a series of guidelines to be presented as a basis for the design of such a tube bank.
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44

Taulbee, Ron J. "Vibro-Acoustic Analysis of a Thin Cylindrical Shell with Minimal Passive Damping Patches." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1367459330.

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45

Cullen, Lachlan Michael. "Acoustic receptivity in boundary layers with surface roughness." Thesis, Queen Mary, University of London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327024.

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46

Taylor, Mark Victor. "Acoustic and instability properties of coaxial jet flows." Thesis, University of Leeds, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238545.

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47

Willison, Peter A. "Transmission line matrix modelling of underwater acoustic propagation." Thesis, University of Essex, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334426.

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48

Blondel, Laurent Armand. "Compressed air acoustic sources for active noise control." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246196.

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49

Beckett, Carolyn. "Studies of acoustic scattering using a parametric array." Thesis, University of Bath, 1992. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332293.

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50

Shehan, Joe Michael. "Stability analysis of a 2-D acoustic/structure model." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA303097.

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