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Acoustic sources in motionDowling, Ann Patricia January 1978 (has links)
The motion of an acoustic source changes its sound field. Three fundamental topics concerned with radiation from moving sources are investigated in this thesis. In the first we consider the effect of motion on the sound field of two of the simplest realistic sources, a pulsating and a vibrating body. These two problems are often misrepresented as a moving monopole and dipole respectively. But it is found that for real sources that motion introduces additional coupled multipoles whose combined effect generates previously unexpected features. In general the change in the sound field due to source motion is greater than the effect estimated from previous mathematical models. Moreover, and quite unexpectedly, we have found that the radiation is altered in a direction perpendicular to the flight path. Our second problem concerns the production of sound by a jet stream. We derive a generalization of Lighthill's acoustic analogy to account for the interaction of the acoustic field with the mean jet flow. We prove that the jet noise problem can be modelled exactly by convected quadrupoles near a vortex sheet. Each moving fluid particle supports a quadrupole whose strength is given by Lighthill's stress tensor and the sound radiates as if it were adjacent to an instability-free vortex sheet. Although we show that the sound field may be expressed in terms of the turbulence stress tensor, sound is also generated by the flow's instability waves as they grow into turbulence, and this sound appears as an exponentially growing precursor to the main field. Some well known features of the mean flow acoustic interaction issue are an immediate consequence of the theory. We examine the case of a round jet in some detail and concentrate on a new aspect. When the jet density is much lower than that of its environment, the mean flow acoustic interaction results in a considerable amplification of the quadrupole field and the intensity of its sound can scale on an unusually low power of the jet speed. We show that a fourth power law is possible and even a second power law when the density difference is large enough. This may be part of the "excess noise" problem in which the sound of engine produced hot jets is often insensitive to changes in jet speed at low exhaust power. A modern rotary printing press, is a noisy machine. One of the noise sources is the vibration of the paper web as it moves under variable tension between the rollers. Our third problem models this process. We consider a semi-infinite elastic sheet initially at rest with a prescribed displacement. The sound produced by suddenly tugging one end is investigated. It is found that a tension wave travels supersonically through the sheet. There is no motion ahead of this wave but behind it the tensioned sheet supports a vibration. A membrane excited in this way is silent except at the tugged end and at the tension front. The sound field has all the characteristics of a moving line source. The parameters that control the noise output are identified and the dependence of the sound field on these variables is determined.
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The music-archaeology of the Palaeolithic within its cultural settingScothern, Paula Marie Theresa January 1993 (has links)
A consideration of the music-archaeological evidence of the Upper Palaeolithic from Aurignacian onwards, set within the cultural and anatomical context of its creators: examining its evolutionary relationship with the events of the Mousterian and with successive musical-cultural behaviour during the Mesolithic and Neolithic of Europe. The work builds upon study undertaken as an undergraduate and M.Mus. student, and is the culmination of four years' research at Cambridge. The work is designed to be both a theoretical and practical approach, the product of a thorough documentary survey of literature from several disciplines, contacts with major European institutions, fieldwork abroad and the replication of selected Palaeolithic sound-producers. The first section, devoted to the origins of musical behaviour, explores the relationship between conceptualisation, behaviour and sound alongside major evolutionary developments such as speech, locomotion, manual skills and other forms of non-verbal communication. The Middle-Upper Palaeolithic transition is presented as the scenario for the appearance of the sound-producer, and Section 2 outlines the cultural and sociological factors which distinguish Mousterian and Upper Palaeolithic populations. The discovery of the sound-producing mechanism is s.t:en as an outgrowth of bone-working traditions established during the Aurignacian, as a reflection of subsistence strategies adopted by Palaeolithic groups - a mechanism which was to culminate in the advanced forms of the Magdalenian. The discussion focuses upon two major collections from the French sites of Isturitz and Le Placard, and explores how the musical cultures of the Mesolithic and Neolithic may be a continuation of the Palaeolithic, or an adaptation of these traditions to new materials, environments and subsistence strategies. The development of the soundproducer during the post-glacial is considered as part of a wider process of demographic expansion throughout Scandinavia, the Far East, and the New World. The concluding chapter presents a synthesis and overview of the earlier discussion. Examining the relationship between the sound-producer and vocal forms of musical behaviour, it looks more closely at the distinction between technological and conceptual definitions of "music". In attempting to place prehistoric musical behaviour in evolutionary and cultural perspective, it stresses the need to re-examine our own definitions, terminologies and concepts; and ultimately arrives at the question: is it possible to talk of a "concept of music" in prehistory?
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An approach to the analysis of sound in auditoria : model design and computer implementationMoore, Gregg Raymond January 1985 (has links)
No description available.
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Theory of the phonon broadening of impurity spectral lines.Nishikawa, Kyoji January 1962 (has links)
The theory of the phonon broadening of impurity spectral lines in homopolar semi-conductors is discussed within the framework of a Kubo-type formulation of the adiabatic dielectric susceptibility and the subsequent calculation of this using the double-time Green's function method. The basic assumption is the smallness of the interaction of the electrons (or holes) bound to impurity sites with the lattice vibrations. This interaction is then treated as a small perturbation of the independent systems of electron and vibrating lattice; the use of the adiabatic approximation is thereby avoided. The so-called decoupling of the infinite hierarchy of equations for the relevant Green's functions is discussed in detail and is given its justification in the present problem. In the case of nondegenerate electronic levels, the line-shape function is obtained explicitly in terms of the matrix elements of the electron-phonon interaction. It is found that the absorption line consists of a sharp peak with a width arising from a finite life-time of the unperturbed states due to the electron-phonon interaction and of a continuous background arising from the multi-phonon processes which accompany the optical absorption. In the degenerate case, a general method of obtaining the line-shape function is discussed and is illustrated in an example. The results are compared with those obtained by previous workers in the field.
The general theory is applied to shallow impurity levels in silicon with the use of a modified hydrogenic model and a deformation potential description of the electron-phonon interaction; numerical estimates are made for typical contributions to the widths of the lines in both acceptor and donor cases. / Science, Faculty of / Physics and Astronomy, Department of / Graduate
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Wave-guide propagation of acoustic-gravity waves in an isothermal layer model of the stratosphereMcReynolds, William Peter January 1965 (has links)
It is suggested that the stratosphere may-act as a wave-guide for certain types of acoustic-gravity waves. An isothermal layer model is proposed which introduces gravity terms into the equations governing wave propagation. An expression for the phase change on reflection at a boundary of the layer is derived. Numerical solutions to the equation for wave-guide, modes of propagation are obtained by the use of a digital computer.
Results are given in the form of dispersion curves. Cutoff is found to occur at a frequency well above the Brunt resonant frequency for the stratosphere. The model stratosphere proposed in this study does not behave as a lossless wave-guide for gravity coupled acoustic waves. This is shown to be consistent with the results of a more complete study by Press and Harkrider. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate
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The geology and mineralogy of the Yreka copper property, Quatsino Sound, British ColumbiaWilson, Philip Roy January 1955 (has links)
The Yreka copper property is situated on the
west side of Neroutsos Inlet about nine miles northwest
of Port Alice In the northern part of Vaneouver Island,
British Columbia. The property is underlain by rooks of
the Vancouver Group, including greenstones, limestones,
breccias and tuffs striking approximately northwest and
dipping southwest into the mountainside at about 35 degrees.
They, are intruded by dykes and sills of quartz-feldspar
porphyry, quarts diorite and basalt.
The mineral deposits are located in large bodies
of skarn which have been formed in the tuffaceous rocks of
the middle part of the sequence. The skarn zones consist
roughly of three subparallel units which appear to conform
approximately with the bedding. The largest of these
skarn zones is about 1500 feet long and more than 100 feet
wide, and contains sulphide bodies of economic interest.
Other sulphide showings have been found on the property but
do not appear to be of economic significance. The skarn
zones are of pyrometasomatic origin of the type not related
to an igneous contact.
Development work in the early part of the century
included stripping and trenching, driving a number of adits
in various places in the skarn zones, and mining of a small
tonnage of ore. Recent work, consisting of mapping, sampling and diamond drilling, has shown the property to
be a prospect of considerable merit. / Arts, Faculty of / Geography, Department of / Graduate
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Archaeological investigations at Nootka Sound, Vancouver Island.McMillan, Alan D. January 1969 (has links)
The archaeology of the Moachat Nootka territory, consisting of Nootka Sound and Tahsis and Tlupana Inlets, was chosen as the specific concern of this thesis. Nootka Sound was an important area in the early historic fur trade and a great deal was written by the early explorers and traders about the inhabitants of this region. However, little archaeological work has been done. A large-scale excavation, carried out at the main Moachat village of Yukwot in 1966 by the National Historic Parks Branch, was the only previous archaeological project. As the material obtained by this excavation had not been published or fully processed at the time of writing, very little of the information was available for the present study. The objectives of the fieldwork were: to visit and describe the sixteen villages and camp sites listed for the Moachat by Drucker (1951: 229), to carry out excavations at one of these sites, to visit and describe the burial caves and pictographs which were known to exist in the area, and to collect whatever ecological and ethnographic information could be conveniently obtained. No site survey was undertaken, although a few previously unrecorded sites were discovered.
Excavations were carried out at Coopte (DkSp 1), the winter village of the Moachat, during the summer of 1968. The excavations were rather small in scope, lasting only two months and being conducted sometimes by myself only and sometimes with the help of one assistant. Nevertheless, fifteeen test pits were excavated which yielded 273 artifacts and a fair sample of faunal remains and historic material.
This paper includes an account of the excavations at Coopte, as well as descriptions of the other sites visited. It is also an attempt to integrate historic and ethnographic information with the archaeological data. The substantial body of published and unpublished information provides a convenient basis for the interpretation of the archaeological material. It is hoped that this approach will prove useful in attempting to describe the way of life of the aboriginal inhabitants of Nootka Sound. / Arts, Faculty of / Anthropology, Department of / Graduate
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Portfolio of original compositions and analytical commentarySarsfield, Donal Robert January 2014 (has links)
This portfolio of original compositions investigates how a concentrated perspective on one particular sound source has the potential to develop a perceptual link between the listener, the work and the world in which we live. To this end a contradictory approach to organising sound is employed; sounds are chosen for their intrinsic properties but are never fully removed from their referential identity. This approach is framed within a broad awareness of cultural listening, which recognises the value of the sound sources in society, but within the confines of the work these sounds operate with neutral symbolic function in order to emphasise their morphological identity. The commentary discusses the main issues arising relating to the composition of the six works in the portfolio, namely the recording, transformation and organising of recorded sound.
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A Real-Time Electronic Sound Analysis System with Graphical User InterfaceBrgulja, Amir 08 1900 (has links)
Noise-induced hearing loss is a serious problem common to musical environments. Current dosimetry technology is primarily designed for industrial environments and not suited for musical settings. At present, there are no government regulations that apply to the educational music environment as it relates to monitoring and prevention of hearing loss. Also, no system exists than can serve as a proactive tool in observation and reporting of sound exposure levels with the goal of hearing conservation. Newly proposed system takes a software based approach in designing a proactive dosimetry system that can assess the risk of sound noise exposure. It provides real-time feedback trough a graphical user interface that is capable of database storage for further study.
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Design Approaches to Alert Sounds for Interactions in ShopsAnindita, Puspita Parahita January 2021 (has links)
Shoplifting is a serious issue that causes loss to retail owners. However, the loss can be avoided by adding preventative measures to deter shoplifters from committing the crime. Surveillance [2] and a store's design and layout [3] are considered significant factors that could deter them. Considering that background music is a part of a store's design, this research combined surveillance and a store's design to discourage shoplifters by creating changes to the background music that could make the shoplifters feel observed. Ultimately, this research asked these questions: 1) If a change in background music could make the visitor feel observed, what are the possible design strategies? and 2) which design is preferable? In this research, eight participants watched a first-person view of a shopper going around the shop and lifting a clothing article. The participants were asked to create a sound alert that matched the lifting action, mixed with three different background music tracks. Afterwards, they were asked to hand in the documentation of their design. Apart from that, they were asked to fill in a quantitative survey evaluating all the designs (including other participants' designs) and describe the design with three keywords. This research discovered that there were three main approaches in designing the sound alert, and there were certain preferences of a design approach dependent on the type of background music. In other words, there is a correlation between the type of background music and the preferred design approach. This work also discussed its limitations and presented opportunities for future research. / Snatteri är ett allvarligt problem som orsakar förluster för butiksägare. Förlusterna kan dock undvikas genom förebyggande åtgärder för att avskräcka butikstjuvarna från att begå brottet. Övervakning [2] samt butikens design och planlösning [3] anses vara viktiga faktorer som kan avskräcka dem. Med tanke på att bakgrundsmusik är en del av en butikens design kombinerar denna forskning övervakning och butikens design för att avskräcka snattare genom att skapa förändringar i bakgrundsmusiken som kan få snattarna att känna sig observerade. Avslutningsvis ställde den här forskningen dessa frågor: 1) Om en förändring av bakgrundsmusiken kan få besökaren att känna sig observerad, vilka är då de möjliga designstrategierna? och 2) Vilken design är att föredra? I den här forskningen tittade åtta deltagare på en shoppare från hen som går runt i butiken och lyfter ett klädesplagg. Deltagarna ombads att skapa ett ljudlarm som matchade lyfthandlingen, blandat med tre olika bakgrundsmusikspår. Efteråt ombads de att lämna in dokumentationen av sin design. Dessutom ombads de att fylla i en kvantitativ enkät där de utvärderade alla konstruktioner (inklusive andra deltagares konstruktioner) och beskrev konstruktionen med tre nyckelord. Forskningen visade att det fanns tre huvudsakliga tillvägagångssätt vid utformningen av ljudvarningen, och att det fanns vissa preferenser för ett tillvägagångssätt beroende på typen av bakgrundsmusik. Med andra ord finns det en korrelation mellan typen av bakgrundsmusik och den föredragna designmetoden. I detta arbete diskuterades också dess begränsningar och presenterades möjligheter för framtida forskning.
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