This book presents a three-dimensional analysis of acoustic wave propagation in an elliptical waveguide, and applies the equations and concepts to design axially short elliptical end-chamber muffler configurations which are an important component of a complex multi-pass muffler used in a modern-day automotive exhaust system. A general solution of the Helmholtz equation in elliptical cylindrical co-ordinates is presented in terms of the Mathieu and modified Mathieu modal functions. This is followed by the tabulation and analysis, for the first time, of the non-dimensional resonance frequencies of the transverse modes of a rigid-wall elliptical waveguide for a complete range of aspect ratio. The modal shape patterns of the first few circumferential, radial and cross-modes are examined with particular attention to the pressure nodal ellipses and hyperbolae. An analytical formulation is then outlined for characterizing a single-inlet and single-outlet elliptical muffler with the inlet located on the end face and the outlet located either on the end face or side-surface. The ensuing chapter is devoted toward analyzing the Transmission Loss (TL) performance of different short end-chamber mufflers, namely (a) the straight-flow configuration having ports located on the opposite face, (b) the flow-reversal configuration with ports located on the same end face and (c) configuration with inlet port on the end face and outlet on the side surface. Design guidelines are formulated in terms of the optimal location of inlet and outlet ports which suppresses the deteriorating influence of certain higher-order modes, thereby delivering a broadband TL performance. Directions for future work are discussed toward the end. In summary, this book is a one-stop solution for a practicing automotive engineer designing mufflers, for an applied mathematician studying wave propagation in elliptical geometries, and also as a niche area within noise control engineering.

This book presents a comprehensive overview of hydroacoustics and describes the physical basis of acoustic processes observed in the sea. In addition, it discusses the basic concepts and provides simplified models of sound propagation and acoustic phenomena at the boundary between environments. Lastly, the book examines in detail a number of applications of ocean acoustics and methods. The ocean is the last reserve of natural resources. It is also an essential element in the biosphere, ensuring the latter's balance, and plays a pivotal role in the Earth's climate system and global warming. Consequently, studying the ocean is one of humankind's most critical scientific tasks, but penetrating its mysteries is no mean feat. Acoustics (hydroacoustics) is one of the most powerful tools for examining the water layer and beyond, since sound waves are the only type of radiation that can propagate over distances of hundreds and even thousands of kilometers in the ocean. This unique resource appeals to specialists working in the fields of ocean and atmosphere physics, students and postgraduate students studying sea physics and oceanology, and anyone who is interested in the problems the ocean is currently facing.

The focus of this thesis are synchronization phenomena in networks and their intrinsic control through time delay, which is ubiquitous in real-world systems ranging from physics and acoustics to neuroscience and engineering. We encounter synchronization everywhere and it can be either a helpful or a detrimental mechanism. In the first part, after a survey of complex nonlinear systems and networks, we show that a seemingly simple system of two organ pipes gives birth to complex bifurcation and synchronization scenarios. Going from a 2-oscillator system to a ring of oscillators, we encounter the intriguing phenomenon of chimera states which are partial synchrony patterns with coexisting domains of synchronized and desynchronized dynamics. For more than a decade scientist have tried to solve the puzzle of this spontaneous symmetry-breaking emerging in networks of identical elements. We provide an analysis of initial conditions and extend our model by the addition of time delay and fractal connectivities. In the second part, we investigate partial synchronization patterns in a neuronal network and explain dynamical asymmetry arising from the hemispheric structure of the human brain. A particular focus is on the novel scenario of partial relay synchronization in multiplex networks. Such networks allow for synchronization of the coherent domains of chimera states via a remote layer, whereas the incoherent domains remain desynchronized. The theoretical framework is demonstrated with different generic models.

Dieser Bericht behandelt die akustischen Aspekte der sprachlichen Kommunikation, insbesondere wenn sie durch Gerausche, Nachhall oder Schwerhorigkeit gestort ist. Produktion und Wahrnehmung von Sprache, also Sprechen und Horen, dienen wesentlich der Integration eines Menschen in das soziale und kulturelle Leben. Beides ist die Voraussetzung fur ein kompetentes Verhalten in der Familie, in der Offentlichkeit, am Arbeitsplatz und in der Ausbildung. Der Fortschritt der Technik verlangt notwendig nach mehr Kommunikation: u.a. aufgrund veranderter Betriebsablaufe (Teamarbeit zur Verbindung von Entwicklung, Konstruktion, Produktion, Verteilung der Arbeit an unterschiedlichen Standorten), an mobilen Arbeitsplatzen, bei der Benutzung akustischer Medien oder mobiler Telefone und beim weltweiten Kommunizieren in einer Zweitsprache. Die Auswirkungen reduzierter Kommunikation aufgrund von Larm oder Schwerhorigkeit sind deshalb betrachtlich. Durch akustisch schlecht gestaltete Raume, Arbeitsplatze und Kommunikationsgerate und durch zu hohe Sprechpegel, z.B. aus Lautsprechern, wird die Sprachkommunikation zusatzlich eingeschrankt. Damit ist nicht nur Wahrnehmen und Verstehen von Sprache reduziert, sondern zwingend auch der Informationsaustausch: die private, soziale und betriebliche Interaktion. Zu beachten sind ebenso auch langfristige Folgen, wie z.B. ein verzogerter Spracherwerb in Kindergarten und Schule, die Abnahme der Qualitat der Arbeit, die Zunahme von Konflikten und von Unfallen am Arbeitsplatz und eine Verminderung der physischen und psychischen Gesundheit. Ausgangspunkt der Analyse ist das Sprecher-Horer-Modell im Kontext der Psychoakustik. Einleitend werden wichtige Grundlagen des Sprechens, der Sprache, der Wahrnehmung und des Verstehens von Sprache dargestellt: der Sprecher produziert Sprache (Sprechweise, Artikulation), die zum Horer im Raum oder uber elektroakustische Anlagen ubertragen wird und gestort werden kann (Bandbegrenzung, Gerausche, Nachhall, Ubersteuerung etc.). Der Horer muss die Sprache wahrnehmen und verstehen, auch wenn er schwerhorig ist oder Gehorschutz tragt. Die Messung der Sprachverstandlichkeit wird anhand der Sprachindices erlautert. Die Methoden zur Bestimmung der Qualitat der Sprachkommunikation werden aufbauend auf der Verstandlichkeit durch Parameter wie Konzentration und Belastigung erganzt und neu formuliert. Die so entwickelten Qualitatsstufen werden ausfuhrlich diskutiert, dazu werden Kriterien fur die Raumgestaltung (u.a. Schulen) abgeleitet. Die Analyse soll es ermoglichen, den Umgebungsbereich fur sprachliche Kommunikation "barrierefrei" zu gestalten, so dass die Kommunikationspartner ungeachtet ihres Alters, individueller Handicaps (begrenzte Sprachkompetenz, Schwerhorigkeit) in offentlichen Bereichen und in der Arbeitswelt als gleichberechtigte Partner am Gesprach teilnehmen konnen. Ziel dieses Buches ist es auch uber die Akustik hinaus einen grossen Leserkreis unterschiedlicher Interessen und Berufsgruppen wie Ergonomen, Psychologen, Mediziner, Architekten, Medienexperten in die Diskussion uber die Sprachkommunikation aus wissenschaftlicher und angewandter Sicht einzufuhren und Hinweise fur eine optimale Gestaltung zu geben."

The inverse scattering problem is central to many areas of science and technology such as radar, sonar, medical imaging, geophysical exploration and nondestructive testing. This book is devoted to the mathematical and numerical analysis of the inverse scattering problem for acoustic and electromagnetic waves. In this fourth edition, a number of significant additions have been made including a new chapter on transmission eigenvalues and a new section on the impedance boundary condition where particular attention has been made to the generalized impedance boundary condition and to nonlocal impedance boundary conditions. Brief discussions on the generalized linear sampling method, the method of recursive linearization, anisotropic media and the use of target signatures in inverse scattering theory have also been added.

This book describes the entire process of designing guitars, including the theory and guidelines for implementing it in practice. It discusses areas from acoustics and resonators to new tools and how they assist traditional construction techniques. The book begins by discussing the fundamentals of the sounds of a guitar, strings, and oscillating systems. It then moves on to resonators and acoustics within the guitar, explaining the analysis systems and evaluation methods, and comparing classic and modern techniques. Each area of the guitar is covered, from the soundboard and the back, to the process of closing the instrument. The book concludes with an analysis of historic and modern guitars. This book is of interest to luthiers wanting to advance their practice, guitar players wishing to learn more about their instruments, and academics in engineering and physics curious about the principles of acoustics when applied to musical instruments.

This book gathers contributions on various aspects of the theory and applications of linear and nonlinear waves and associated phenomena, as well as approaches developed in a global partnership of researchers with the national Centre of Excellence in Nonlinear Studies (CENS) at the Department of Cybernetics of Tallinn University of Technology in Estonia. The papers chiefly focus on the role of mathematics in the analysis of wave phenomena. They highlight the complexity of related topics concerning wave generation, propagation, transformation and impact in solids, gases, fluids and human tissues, while also sharing insights into selected mathematical methods for the analytical and numerical treatment of complex phenomena. In addition, the contributions derive advanced mathematical models, share innovative ideas on computing, and present novel applications for a number of research fields where both linear and nonlinear wave problems play an important role. The papers are written in a tutorial style, intended for non-specialist researchers and students. The authors first describe the basics of a problem that is currently of interest in the scientific community, discuss the state of the art in related research, and then share their own experiences in tackling the problem. Each chapter highlights the importance of applied mathematics for central issues in the study of waves and associated complex phenomena in different media. The topics range from basic principles of wave mechanics up to the mathematics of Planet Earth in the broadest sense, including contemporary challenges in the mathematics of society. In turn, the areas of application range from classic ocean wave mathematics to material science, and to human nerves and tissues. All contributions describe the approaches in a straightforward manner, making them ideal material for educational purposes, e.g. for courses, master class lectures, or seminar presentations.

This book summarizes the latest research on cognitive network-layer methods and smart adaptive physical-layer methods in underwater networks. Underwater communication requires extendable and delay-tolerant underwater acoustic networks capable of supporting multiple frequency bands, data rates and transmission ranges. The book also discusses a suitable foreground communication stack for mixed mobile/static networks, a technology that requires adaptive physical layer waveforms and cognitive network strategies with underlying cooperative and non-cooperative robust processes. The goal is to arrive at a universally applicable standard in the area of Underwater Internet-of-Things [ISO/IEC 30140, 30142, 30143].  The book is the second spin-off of the research project RACUN, after the first RACUN-book "Underwater Acoustic Networking Techniques" (https://link.springer.com/book/10.1007%2F978-3-642-25224-2)

This volume collects the papers from the World Conference on Acoustic Emission 2017 (WCAE-2017) in Xi'an, China. The latest research and applications of acoustic emission (AE) are explored, with a particular emphasis on detecting and processing AE signals, the development of AE instrument and testing standards, AE of materials, engineering structures and systems, including the processing of collected data and analytical techniques. Numerous case studies are also included. This proceedings volume will appeal to students, professors and researchers working in these fields as physicists and/or engineers.

This book highlights the acoustic performance of concrete made with Coal Bottom Ash (CBA) that has contributed to environmental issues. The usage of CBA in concrete can be recommended as good concrete due to its absorption properties. This book focuses on the principles and techniques employed in acoustic design. The book first elaborates on the perception of noise and properties of noise, followed by physical data, units and measurements. Finally, it takes a look at acoustic analysis which includes acoustic performance effects using different volumes of CBA, density and porosity of concrete.

This book provides a broad overview of spaciousness in music theory, from mixing and performance practice, to room acoustics, psychoacoustics and audio engineering, and presents the derivation, implementation and experimental validation of a novel type of spatial audio system. Discussing the physics of musical instruments and the nature of auditory perception, the book enables readers to precisely localize synthesized musical instruments while experiencing their timbral variance and spatial breadth. Offering interdisciplinary insights for novice music enthusiasts and experts in the field of spatial audio, this book is suitable for anyone interested in the study of music and musicology and the application of spatial audio mixing, or those seeking an overview of the state of the art in applied psychoacoustics for spatial audio.

This book highlights the symmetry properties of acoustic fields and describes the gauge invariance approach, which can be used to reveal those properties. Symmetry is the key theoretical framework of metamaterials, as has been demonstrated by the successful fabrication of acoustical metamaterials. The book first provides the necessary theoretical background, which includes the covariant derivative, the vector potential, and invariance in coordinate transformation. This is followed by descriptions of global gauge invariance (isotropy), and of local gauge invariance (anisotropy). Sections on time reversal symmetry, reflection invariance, and invariance of finite amplitude waves round out the coverage.

This book addresses the peculiarities of nonlinear wave propagation in waveguides and explains how the stratification depends on the waveguide and confinement. An example of this is an optical fibre that does not allow light to pass through a density jump. The book also discusses propagation in the nonlinear regime, which is characterized by a specific waveform and amplitude, to demonstrate so-called solitonic behaviour. In this case, a wave may be strongly localized, and propagates with a weak change in shape. In the waveguide case there are additional contributions of dispersion originating from boundary or asymptotic conditions. Offering concrete guidance on solving application problems, this essentially (more than twice) expanded second edition includes various aspects of guided propagation of nonlinear waves as well as new topics like solitonic behaviour of one-mode and multi-mode excitation and propagation and plasma waveguides, propagation peculiarities of electromagnetic waves in metamaterials, new types of dispersion, dissipation, electromagnetic waveguides, planetary waves and plasma waves interaction.The key feature of the solitonic behaviour is based on Coupled KdV and Coupled NS systems. The systems are derived in this book and solved numerically with the proof of stability and convergence. The domain wall dynamics of ferromagnetic microwaveguides and Bloch waves in nano-waveguides are also included with some problems of magnetic momentum and charge transport.

The 20th century saw radical changes in the way serious music is composed and produced, including the advent of electronic instruments and novel compositional methods such as serialism and stochastic music. Unlike previous artistic revolutions, this one took its cues from the world of science. Creating electronic sounds, in the early days, required a well-equipped laboratory and an understanding of acoustic theory. Composition became increasingly "algorithmic", with many composers embracing the mathematics of set theory. The result was some of the most intellectually challenging music ever written - yet also some of the best known, thanks to its rapid assimilation into sci-fi movies and TV shows, from the electronic scores of Forbidden Planet and Dr Who to the other-worldly sounds of 2001: A Space Odyssey. This book takes a close look at the science behind "science fiction" music, as well as exploring the way sci-fi imagery found its way into the work of musicians like Sun Ra and David Bowie, and how music influenced the science fiction writings of Philip K. Dick and others.

Both an original contribution and a lucid introduction to mathematical aspects of fluid mechanics, "Navier-Stokes Equations" provides a compact and self-contained course on these classical, nonlinear, partial differential equations, which are used to describe and analyze fluid dynamics and the flow of gases.

This book discusses the applications of signal and image processing in acoustical imaging. It first describes the basic tools involved - the 2D transform, fast Fourier transform (FFT) and applications, and deconvolution - before introducing readers to higher-order statistics, wavelets, and neural networks. It also addresses the important topic of digital signal processing, focusing on the example of homomorphic signal processing. The book then details the design of digital filters and array signal processing, and lastly examines applications in image processing: image enhancement and optimization, image restoration, and image compression.

There are many books on finite element methods but few give more than a brief description of their application to structural vibration analysis. This book presents an introduction to the mathematical basis of finite element analysis as applied to vibrating systems. Finite element analysis is a technique that is very important in modeling the response of structures to dynamic loads. Although this book assumes no previous knowledge of finite element methods, those who do have knowledge will still find the book to be useful. It can be utilized by aeronautical, civil, mechanical, and structural engineers as well as naval architects. This second edition includes information on the many developments that have taken place over the last twenty years. Existing chapters have been expanded where necessary, and three new chapters have been included that discuss the vibration of shells and multi-layered elements and provide an introduction to the hierarchical finite element method.

In Moravian Soundscapes, Sarah Eyerly contends that the study of sound is integral to understanding the interactions between German Moravian missionaries and Native communities in early Pennsylvania. In the mid-18th century, when the frontier between settler and Native communities was a shifting spatial and cultural borderland, sound mattered. People listened carefully to each other and the world around them. In Moravian communities, cultures of hearing and listening encompassed and also superseded musical traditions such as song and hymnody. Complex biophonic, geophonic, and anthrophonic acoustic environments-or soundscapes-characterized daily life in Moravian settlements such as Bethlehem, Nain, Gnadenhutten, and Friedenshutten. Through detailed analyses and historically informed recreations of Moravian communal, environmental, and religious soundscapes and their attendant hymn traditions, Moravian Soundscapes explores how sounds-musical and nonmusical, human and nonhuman-shaped the Moravians' religious culture. Combined with access to an interactive website that immerses the reader in mid-18th century Pennsylvania, and framed with an autobiographical narrative, Moravian Soundscapes recovers the roles of sound and music in Moravian communities and provides a road map for similar studies of other places and religious traditions in the future.

This unique one-volume overview of classical wave theory-ideal as a classroom text or for individual study-covers wave phenomena of acoustics, optics, electromagnetic radiations and more. Topics include fundamentals, Bessel functions, waveguides, elasticity theory, hydrodynamic waves, and special phenomenon of wave diffraction. With problems.

These proceedings primarily focus on advances in the theory, experiments, and numerical simulations of turbulence in the contexts of flow-induced vibration and noise, as well as their control. Fluid-related structural vibration and noise problems are often encountered in many engineering fields, increasingly making them a cause for concern. The FSSIC conference, held on 5-9 July 2015 in Perth, featured prominent keynote speakers such as John Kim, Nigel Peake, Song Fu and Colin Hansen, as well as talks on a broad range of topics: turbulence, fluid-structure interaction, fluid-related noise and the control/management aspects of these research areas, many of which are clearly interdisciplinary in nature. It provided a forum for academics, scientists and engineers working in all branches of Fluid-Structure-Sound Interactions and Control (FSSIC) to exchange and share the latest developments, ideas and advances, bringing them together researchers from East and West to push forward the frontiers of FSSIC, ensuring that the proceedings will be of interest to a broad engineering community.

The limiting influence of the environment on sonar has long been recognised as a major challenge to science and technology. As the area of interest shifts towards the lit toral, environmental influences become dominant both in time and space. The manyfold challenges encompass prediction, measurement, assessment and adaptive responses to maximize the effectiveness of systems. Although MCM and ASW activities are dom inated in different ways and scales by the environment, both warfare areas have had to consider the significantly changing requirements posed by operations in the littoraL The fundamental scientific issues involved in developing models relating acoustics to the environment are matched in difficulty by the need for data for their validation and eventual practical use for prediction. In many instances the need is for on-line adaptation of systems to changing circumstances whilst other needs are for the Ionger term planning activities. This book and the attached full-color CD are the proceedings of a conference organ ised by the SACLANT Undersea Research Centre, held at Villa Marigola, Lerici, Italy, on 16-20 September 2002. The fundamental problems associated with environmental 1 variability and sonar were explored at a previous SACLANTCEN conference in 1990. These problems have not gone away but, on the one hand are exaggerated by the move to the littoral and on the other hand, are open to treatrnent in new ways that advances in technology and computer power allow.

This book provides a comprehensive introduction to the theory and practice of spherical microphone arrays, and was written for graduate students, researchers and engineers who work with spherical microphone arrays in a wide range of applications. The new edition includes additions and modifications, and references supplementary Matlab code to provide the reader with a straightforward start for own implementations. The book is also accompanied by a Matlab manual, which explains how to implement the examples and simulations presented in the book. The first two chapters provide the reader with the necessary mathematical and physical background, including an introduction to the spherical Fourier transform and the formulation of plane-wave sound fields in the spherical harmonic domain. In turn, the third chapter covers the theory of spatial sampling, employed when selecting the positions of microphones to sample sound pressure functions in space. Subsequent chapters highlight various spherical array configurations, including the popular rigid-sphere-based configuration. Beamforming (spatial filtering) in the spherical harmonics domain, including axis-symmetric beamforming, and the performance measures of directivity index and white noise gain are introduced, and a range of optimal beamformers for spherical arrays, including those that achieve maximum directivity and maximum robustness are developed, along with the Dolph-Chebyshev beamformer. The final chapter discusses more advanced beamformers, such as MVDR (minimum variance distortionless response) and LCMV (linearly constrained minimum variance) types, which are tailored to the measured sound field. Mathworks kindly distributes the Matlab sources for this book on https://www.mathworks.com/matlabcentral/fileexchange/68655-fundamentals-of-spherical-array-processing.

This book provides the first comprehensive overview of the fascinating topic of audio source separation based on non-negative matrix factorization, deep neural networks, and sparse component analysis. The first section of the book covers single channel source separation based on non-negative matrix factorization (NMF). After an introduction to the technique, two further chapters describe separation of known sources using non-negative spectrogram factorization, and temporal NMF models. In section two, NMF methods are extended to multi-channel source separation. Section three introduces deep neural network (DNN) techniques, with chapters on multichannel and single channel separation, and a further chapter on DNN based mask estimation for monaural speech separation. In section four, sparse component analysis (SCA) is discussed, with chapters on source separation using audio directional statistics modelling, multi-microphone MMSE-based techniques and diffusion map methods. The book brings together leading researchers to provide tutorial-like and in-depth treatments on major audio source separation topics, with the objective of becoming the definitive source for a comprehensive, authoritative, and accessible treatment. This book is written for graduate students and researchers who are interested in audio source separation techniques based on NMF, DNN and SCA.

This thesis provides an innovative strategy for rail crack monitoring using the acoustic emission (AE) technique. The field study presented is a significant improvement on laboratory studies in the literature in terms of complex rail profile and crack conditions as well as high operational noise. AE waves induced by crack propagation, crack closure, wheel-rail impact and operational noise were obtained through a series of laboratory and field tests, and analyzed by wavelet transform (WT) and synchrosqueezed wavelet transform (SWT). A wavelet power-based index and the enhanced SWT scalogram were sequentially proposed to classify AE waves induced by different mechanisms according to their energy distributions in the time-frequency domain. A novel crack sizing method taking advantage of crack closure-induced AE waves was developed based on fatigue tests in the laboratory. The propagation characteristics of AE waves in the rail were investigated, and Tsallis synchrosqueezed wavelet entropy (TSWE) with time was finally brought forward to detect and locate rail cracks in the field. The proposed strategy for detection, location and sizing of rail cracks helps to ensure the safe and smooth operation of the railway system. This thesis is of interest to graduate students, researchers and practitioners in the area of structural health monitoring.