Bølgemekanik (vibration og akustik)

This book provides the material for an introductory course in engineering acoustics for students with basic knowledge in mathematics. It is based on extensive teaching experience at the university level. Under the guidance of an academic teacher it is su?cient as the sole te- book for the subject. Each chapter deals with a well de?ned topic and r- resents the material for a two-hour lecture. The chapters alternate between more theoretical and more application-oriented concepts. For the purpose of self-study, the reader is advised to use this text in parallel with further introductory material. Some suggestions to this end are given in Appendix 15. 3. The authors thank Dorea Ruggles for providing substantial stylistic re?- ments. Further thanks go to various colleagues and graduate students who most willingly helped with corrections and proof reading. Nevertheless, the authors assume full responsibility for all contents. Bochum and Troy, Jens Blauert February 2008 Ning Xiang Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1. 1 De?nition of Three Basic Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1. 2 Specialized Areas within Acoustics . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. 3 About the History of Acoustics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. 4 Relevant Quantities in Acoustics . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1. 5 Some Numerical Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1. 6 Levels and Logarithmic Frequency Intervals . . . . . . . . . . . . . . . . . 8 1. 7 Double-Logarithmic Plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2 Mechanic and Acoustic Oscillations . . . . . . . . . . . . . . . . . . . . . . . . 13 2. 1 Basic Elements of Linear, Oscillating, Mechanic Systems . . . . . 14 2. 2 Parallel Mechanic Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2. 3 Free Oscillations of Parallel Mechanic Oscillators . . . . . . . . . . . . 17 2. 4 Forced Oscillation of Parallel Mechanic Oscillators . . . . . . . . . . .

This book delivers a comprehensive and up-to-date treatment of practical applications of metamaterials, structured media, and conventional porous materials. With increasing levels of urbanization, a growing demand for motorized transport, and inefficient urban planning, environmental noise exposure is rapidly becoming a pressing societal and health concern. Phononic and sonic crystals, acoustic metamaterials, and metasurfaces can revolutionize noise and vibration control and, in many cases, replace traditional porous materials for these applications.In this collection of contributed chapters, a group of international researchers reviews the essentials of acoustic wave propagation in metamaterials and porous absorbers with viscothermal losses, as well as the most recent advances in the design of acoustic metamaterial absorbers. The book features a detailed theoretical introduction describing commonly used modelling techniques such as plane wave expansion, multiple scattering theory, and the transfer matrix method. The following chapters give a detailed consideration of acoustic wave propagation in viscothermal fluids and porous media, and the extension of this theory to non-local models for fluid saturated metamaterials, along with a description of the relevant numerical methods. Finally, the book reviews a range of practical industrial applications, making it especially attractive as a white book targeted at the building, automotive, and aeronautic industries.

Listening, Belonging, and Memory puts connected listening at the center of current debates around whose voices might be listened to, who by, and why. Arguing that listening has to be understood in relation to the self, nation, age, witnessing, and memory, it uses examples from digital storytelling, listening projects, and critical media analysis to highlight connections between listening and power. It centers on voices, stories, and silence, how they interweave, and are activated, maneuvered, reconfigured, and denied. It focuses on the small, microengagementsthat crouch within the superstructures of violent border control and the censorious policing of sonic citizenry, identifying cracks in the reshuffling of histories and hierarchies that connected listening affords.

What is the difference between an echo and a reverberation? Where do you best place microphones for that perfect recording? How do you calculate the best note to whistle in a toilet? In this fascinating little book, musician Steve Marshall explores the field of acoustics. From decibels to dolphins, stereo to surround, this book will appeal to singers, musicians, architects, biologists, and anyone who ever wanted to know more about the wonderful world of sound. WOODEN BOOKS US EDITIONS. Small books, BIG ideas. Tiny but packed with information. "Stunning" NEW YORK TIMES. "Fascinating" FINANCIAL TIMES. "Beautiful" LONDON REVIEW OF BOOKS. "Rich and Artful" THE LANCET. "Genuinely mind-expanding" FORTEAN TIMES. "Excellent" NEW SCIENTIST.

This book describes the properties of materials used for making percussion instruments for classical music played by a symphony orchestra in which the instruments could be played as a soloist instrument or as a group or several groups of instruments, as they are included into a musical work. A chapter is devoted to the bells. The scope of this book is primarily confined to percussion instruments of symphony orchestras taking into account the centuries of musical art and tradition. This book bridges the gap in the technical literature on describing the properties of materials for percussion instruments-timpani, other drums, marimba, xylophone, vibraphone, gong, cymbal, triangle, celesta, castanets.