THE SCIENCE AND APPLICATIONS OF ACOUSTICS THE SCIENCE AND APPLICATIONS OF ACOUSTICS SECOND EDITION Daniel R. Raichel CUNY Graduate Center and School of Architecture, Urban Design and Landscape Design The City College of the City University of New York With 253 Illustrations Daniel R. Raichel 2727 Moore Lane Fort Collins, CO 80526 USA [email protected] Library of Congress Control Number: 2005928848 ISBN-10: 0-387-26062-5 eISBN: 0-387-30089-9 Printed on acid-free paper. ISBN-13: 978-0387-26062-4 C 2006 Springer Science+Business Media, Inc. All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, Inc., 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. Printed in the United States of America. (TB/MVY) 987654321 springeronline.com To Geri, Adam, Dina, and Madison Rose Preface The science of acoustics deals with the creation of sound, sound transmission through solids, and the effects of sound on both inert and living materials. As a mechanical effect, sound is essentially the passage of pressure fluctuations through matter as the result of vibrational forces acting on that medium. Sound possesses the attributes of wave phenomena, as do light and radio signals. But unlike its electromagnetic counterparts, sound cannot travel through a vacuum. In Sylva Sylvarum written in the early seventeenth century, Sir Francis Bacon deemed sound to be “one of the subtlest pieces of nature,” but he complained, “the nature of sound in general hath been superficially observed.” His accusation of superficiality from the perspective of the modern viewpoint was justified for his time, not only for acoustics, but also for nearly all branches of physical science. Frederick V. Hunt (1905–1967), one of America’s greatest acoustical pioneers, pointed out that “the seeds of analytical self-consciousness were already there, however, and Bacon’s libel against acoustics was eventually discharged through the flowering of a clearer comprehension of the physical nature of sound.” Modern acoustics is vastly different from the field that existed in Bacon’s time and even 20 years ago. It has grown to encompass the realm of ultrasonics and infrasonics in addition to the audio range, as the result of applications in materi- als science, medicine, dentistry, oceanology, marine navigation, communications, petroleum and mineral prospecting, industrial processes, music and voice synthe- sis, animal bioacoustics, and noise cancellation. Improvements are still being made in the older domains of music and voice reproduction, audiometry, psychoacous- tics, speech analysis, and environmental noise control. This text—aimed at science and engineering majors in colleges and universities, principally undergraduates in the last year or two of their programs and graduation students, as well as practitioners in the field—was written with the assumption that the users of this text are sufficiently versed in mathematics up to and including the level of differential and partial differential equations, and that they have taken the sequence of undergraduate physics courses that satisfy engineering accreditation criteria. It is my hope that a degree of mathematical elegance has been sustained here, even with the emphasis on engineering and scientific applications. While the use of SI units is stressed, very occasional references are made to physical vii viii Preface parameters expressed in English (or Imperial) units. It is strenuously urged that laboratory experience be included in the course (or courses) in which this text is being used. The student of acoustics will thus obtain a far keener appreciation of the topics covered in “recitation” classes when he or she gains “hand on” experience in the use of sound—level meters, signal generators, frequency analyzers, and other measurement tools. Many of the later chapters in the text are self-contained in the sense that an instructor may skip certain segments in order to concentrate on the agenda most appropriate to the class. However, mastery of the materials in the earlier chapters, namely, Chapters 1–6, is obviously requisite to understanding of the later chapters. Chapters such as those dealing with musical instruments or underwater sound propagation or the legal aspects of environmental noise can be skipped in order to accommodate academic schedules or to allow concentration on certain topics of greater interest to the instructor (and, hopefully, his or her class) such as ultrasound, architectural acoustics, or other topics. Problems of different levels of difficulty are included at the end of nearly all of the chapters. Many of the problems entail the theoretical aspects of acoustics, but a number of “practical” questions have also been included. As an author, I hope that I have successfully met the challenge of providing a modern, fairly comprehensive text in the field for the benefit of both students and practitioners, whether they are scientists or engineers. In using parts of this book in prepublication editions in teaching acoustics classes, I have benefited from feedback and suggestions from my students. A number of them have proven to be quite eagle-eyed, as they have supplied a continuous stream of recommendations and corrections, even after the publication of the first edition. It is impossible to acknowledge them all, but Gregory Miller and Jos´e Sinabaldi come to mind as being among the most assiduous. A number of my colleagues and friends have gone through the chapters of the first edition. The real genesis of the first edition occurred when Harry Himmelblau saw the prepublication copy when I was a sum- mer visiting professor at Caltech’s Jet Propulsion Laboratory, and he urged me to consider publication. In particular I must acknowledge Paul Arveson, now retired from the Naval Surface Warfare Center, Carderock of Bethesda, Maryland, who went through the first three chapters with a fine-toothed comb, M. G. Prasad of Stevens Institute of Technology who made a number of extremely valuable sug- gestions for Chapter 9 in instrumentation, and Edith Corliss who greatly encourage me on Chapter 10 dealing with the mechanism of hearing. Dr. Zouhair Lazreq, who did his postdoctorate under my tutelage, also looked over some of the chap- ters, Martin Alexander has been helpful in obtaining illustrations for Chapter 9 in both editions from Br¨uel and Kjær; Dr. Volker Irmer of Germany’s Federal Envi- ronmental Agency introduced me to the European Union’s noise regulations and other international codes, and Armand Lerner arranged to have materials forwarded from Eckel Corporation of Cambridge, Massachusetts. James E. West, formerly of Lucent Bell Laboratories (and now at the Johns Hopkins University) and past president (1998–1999) of the Acoustical Society of America, was instrumental Preface ix in providing photographs of the anechoic chamber. I am also indebted to Caleb Cochran of the Boston Symphony Orchestra, Steve Lowe of the Seattle Symphony Orchestra, Elizabeth Canada of the Kennedy Center, Sandi Brown of the Minnesota Orchestral Association, Rachelle B. Roe of the Los Angeles Philharmonic, Thomas D. Rossing of Northern Illinois University, Ann C. Perlman of the American Insti- tute of Physics, Karen Welty of Abbott Laboratories, Tom Radler of Hohner, Inc., and others, too many to list here, for their help in providing photographs, certain figures, and/or permission to reproduce the figures. I regarded the preparation of this second edition as a splendid opportunity to update The Science and Applications of Acoustics. A number of features have been added to this new edition. Besides the obvious updating of information on acoustic research and applications throughout the text, a section on prosthetic hearing devices was added to Chapter 10; and the original Chapter 17 was split into two chapters, one covering music and music instrumentation and the other dealing with audio processors and sound reproduction. The topic of ultrasound has also been expanded to the extent that two chapters became necessary, with the latter chapter treating the increasingly important topic of medical and industrial applications. An introduction to nonlinear acoustics is provided in Chapter 21. I also must take this opportunity to thank many of my fellow acousticians for their comments and suggestions for the second edition. It is hoped that all of the errors in the first edition has been weeded out and there are precious few, if any, in this volume. Suggestions for improving the text have come from M. G. Prasad, Stevens Institute of Technology; Yves Berthelot, Georgia Institute of Technology; Mark Hamilton, University of Texas at Austin; Neville H. Fletcher, Australian National University; Uwe Hansen, Indiana State; Frank J. Fahy, University of Southhampton; Carleen M. Hutchins, Violin Family Association; and others. Springer-Verlag’s Dr. Hans Koelsch and Ronald Johnson served ably as the editor and acquisitions editor, respectively. Komila Bhat supervised the editing pro- cess and Natacha Menar proved to be instrumental in expediting this publication; their contribution surely helped to improve this second edition. It was a pleasure to work with them. I am still grateful for the past contributions of Dr. Thomas von Foerster and Steven Pisano, who both worked with me at Springer-Verlag on the first edition. Dr. Robert Beyer, the editor of this AIP series dealing with acoustics, provided a great deal of encouragement and inspiration. He has my unbounded admiration (and that of virtually every acoustician) for the range of his knowledge and extraordinary wisdom.