NOISE AND MILITARY SERVICE

Implications for Hearing Loss and Tinnitus

Committee on Noise-Induced Hearing Loss and Tinnitus Associated with Military Service from World War II to the Present

Medical Follow-up Agency

Larry E. Humes, Lois M. Joellenbeck, and Jane S. Durch, Editors

INSTITUTE OF MEDICINE OF THE NATIONAL ACADEMIES

THE NATIONAL ACADEMIES PRESS
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Noise and Military Service: Implications for Hearing Loss and Tinnitus NOISE AND MILITARY SERVICE Implications for Hearing Loss and Tinnitus Committee on Noise-Induced Hearing Loss and Tinnitus Associated with Military Service from World War II to the Present Medical Follow-up Agency Larry E. Humes, Lois M. Joellenbeck, and Jane S. Durch, Editors INSTITUTE OF MEDICINE OF THE NATIONAL ACADEMIES THE NATIONAL ACADEMIES PRESS Washington, DC www.nap.edu

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Noise and Military Service: Implications for Hearing Loss and Tinnitus THE NATIONAL ACADEMIES PRESS 500 Fifth Street, N.W. Washington, DC 20001 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This study was supported by Contract No. V101(93)P-1637 #29 between the National Academy of Sciences and the Department of Veterans Affairs. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the organizations or agencies that provided support for this project. Library of Congress Cataloging-in-Publication Data Noise and military service : implications for hearing loss and tinnitus / Committee on Noise-Induced Hearing Loss and Tinnitus Associated with Military Service from World War II to the Present, Medical Follow-up Agency ; Larry E. Humes, Lois M. Joellenbeck, and Jane S. Durch, editors. p. ; cm. Includes bibliographical references. ISBN 0-309-09949-8—ISBN 0-309-65307-X 1. Deafness—Etiology. 2. Tinnitus—Etiology. 3. Deafness, Noise induced. 4. Acoustic trauma. 5. Soldiers—Health and hygiene. 6. Veterans—Health and hygiene. 7. Noise—Health aspects. I. Humes, Larry. II. Joellenbeck, Lois M. (Lois Mary), 1963- . III. Durch, Jane. IV. Institute of Medicine (U.S.). Committee on Noise-Induced Hearing Loss and Tinnitus Associated with Military Service from World War II to the Present. [DNLM: 1. Noise—adverse effects. 2. Hearing Loss, Noise-Induced. 3. Military Personnel. 4. Tinnitus. WV 270 N7836 2005] RF291.5.S65N65 2005 617.8′07—dc22 2005030236 Additional copies of this report are available from the National Academies Press, 500 Fifth Street, N.W., Lockbox 285, Washington, DC 20055; (800) 624-6242 or (202) 334-3313 (in the Washington metropolitan area); Internet, http://www.nap.edu. For more information about the Institute of Medicine, visit the IOM home page at: www.iom.edu. Copyright 2006 by the National Academy of Sciences. All rights reserved. Printed in the United States of America. The serpent has been a symbol of long life, healing, and knowledge among almost all cultures and religions since the beginning of recorded history. The serpent adopted as a logotype by the Institute of Medicine is a relief carving from ancient Greece, now held by the Staatliche Museen in Berlin.

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Noise and Military Service: Implications for Hearing Loss and Tinnitus “Knowing is not enough; we must apply. Willing is not enough; we must do.” —Goethe INSTITUTE OF MEDICINE OF THE NATIONAL ACADEMIES Advising the Nation. Improving Health.

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Noise and Military Service: Implications for Hearing Loss and Tinnitus THE NATIONAL ACADEMIES Advisers to the Nation on Science, Engineering, and Medicine The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Wm. A. Wulf is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. Wm. A. Wulf are chair and vice chair, respectively, of the National Research Council. www.national-academies.org

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Noise and Military Service: Implications for Hearing Loss and Tinnitus COMMITTEE ON NOISE-INDUCED HEARING LOSS AND TINNITUS ASSOCIATED WITH MILITARY SERVICE FROM WORLD WAR II TO THE PRESENT LARRY E. HUMES (Chair), Professor, Department of Speech and Hearing Sciences, Indiana University ELLIOTT H. BERGER, Senior Scientist, Auditory Research, E•A•R/ Aearo Company, Indianapolis, Indiana BARBARA A. BOHNE, Professor, Department of Otolaryngology, Washington University School of Medicine ANTHONY T. CACACE, Associate Professor, The Neuroscience Institute and Advanced Imaging Research Center, Albany Medical College KAREN J. CRUICKSHANKS, Professor, Department of Ophthalmology and Visual Sciences and Department of Population Health Sciences, University of Wisconsin Medical School RICHARD W. DANIELSON, Manager for Audiology and Hearing Conservation, National Space Biomedical Research Institute, Baylor College of Medicine JUDY R. DUBNO, Professor, Department of Otolaryngology–Head and Neck Surgery, Medical University of South Carolina GEORGE A. GATES, Emeritus Director/Professor, Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology–Head and Neck Surgery, University of Washington School of Medicine DONALD HENDERSON, Professor, Center for Hearing and Deafness, State University of New York at Buffalo JOHN H. MILLS, Professor, Department of Otolaryngology–Head and Neck Surgery, Medical University of South Carolina MARK R. STEPHENSON, Senior Research Audiologist, Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, Ohio RICHARD S. TYLER, Professor and Director of Audiology, Department of Otolaryngology–Head and Neck Surgery, and Department of Speech Pathology and Audiology, The University of Iowa ROBERT B. WALLACE, Irene Ensminger Stecher Professor of Epidemiology and Internal Medicine, Department of Epidemiology, The University of Iowa Project Staff LOIS JOELLENBECK, Senior Program Officer (Study Director) JANE DURCH, Senior Program Officer WILLIAM PAGE, Senior Program Officer

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Noise and Military Service: Implications for Hearing Loss and Tinnitus SUSAN VAN HEMEL, Senior Program Officer, Board on Behavioral, Cognitive, and Sensory Science, Division of Behavioral and Social Sciences and Education KRISTEN GILBERTSON, Research Assistant ALLISON BERGER, Program Assistant KAREN KAZMERZAK, Research Associate RICK ERDTMANN, Director, Medical Follow-up Agency PAMELA RAMEY-MCCRAY, Administrative Assistant ANDREA COHEN, Financial Associate Data Operations HARRIET CRAWFORD, IT Project Manager JOHN LARSON, Records Manager, St. Louis Office NOREEN STEVENSON, Research Assistant AL MATTEI, Staff Assistant

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Noise and Military Service: Implications for Hearing Loss and Tinnitus Reviewers This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the National Research Council’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their review of this report: Bobby R. Alford, Department of Otolaryngology–Head and Neck Surgery, Baylor College of Medicine Robert A. Dobie, Department of Otolaryngology, School of Medicine, University of California, Davis Roger P. Hamernik, Auditory Research Laboratories, State University of New York at Plattsburgh Richard N. Miller, Institute of Medicine (retired) Theresa Y. Schulz, James H. Quillen VA Medical Center, Mountain Home, Tennessee James B. Snow, Jr., National Institute on Deafness and Other Communication Disorders, National Institutes of Health (retired) Evelyn E. Talbott, Department of Epidemiology, University of Pittsburgh William A. Yost, Parmly Hearing Institute and the Graduate School, Loyola University of Chicago

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Noise and Military Service: Implications for Hearing Loss and Tinnitus Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations nor did they see the final draft of the report before its release. The review of this report was overseen by Hyla Napadensky, Napadensky Energetics Inc. (retired), and Linda D. Cowan, Health Sciences Center, University of Oklahoma. Appointed by the National Research Council and Institute of Medicine, they were responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the institution.

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Noise and Military Service: Implications for Hearing Loss and Tinnitus Preface This report represents the collective efforts of many people over a period of approximately 15 months. First and foremost are the committee members, who devoted countless hours of volunteer service to address the committee’s charge. The numerous discussions held, both face to face and via conference calls, were thorough and, when opinions differed, were always conducted with respect for divergent views. The report reflects the broad input and consensus of all committee members and is much stronger as a result. Clearly, the charge could not be addressed without a panel having sufficiently broad areas of expertise, but also a willingness to listen to sometimes differing perspectives with an open mind before moving to consensus. I truly appreciate not only the amount of expertise available through the committee, but the manner in which each member shared that expertise and worked together to meet our collective responsibilities. Another group central to the committee’s work included the staff members from the Institute of Medicine (IOM) and National Research Council (NRC) who supported our efforts. Lois Joellenbeck, who served as study director, and Jane Durch were the committee’s principal guides. We were ably aided as well by research assistant Kristen Gilbertson, whose contributions included not only research and administrative tasks, but also participating in the collection and entry of data from veterans’ medical records. Program assistant Allison Berger managed the logistics of many of the committee’s earlier meetings. Karen Kazmerzak helped initiate our research efforts during the first 3 months of the committee’s work. Susan Van Hemel, a senior program officer with the NRC, contributed advice throughout the study.

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Noise and Military Service: Implications for Hearing Loss and Tinnitus This study included the collection and analysis of data from the service medical records of some 3,500 veterans by members of the staff of the Medical Follow-up Agency of the IOM. The large data collection and data management task was overseen by Harriet Crawford, with the work of data collection and entry performed by Noreen Stevenson, John Larson, and Al Mattei. The data analysis was performed by William Page, a biostatistician with the Medical Follow-up Agency. Identifying and obtaining these records required the assistance of personnel from the Department of Veterans Affairs, the Department of Defense, and the National Archives and Records Administration. On behalf of the committee and staff, I want to thank the many individuals from those agencies for their assistance, and to offer special thanks to Lynda Russell, Yvonne Hamilton, and James White from the Department of Veterans Affairs. The work of the committee was also supported by other staff members from the Medical Follow-up Agency, particularly the director, Rick Erdtmann, and the administrative assistant, Pamela Ramey-McCray. In addition, on behalf of the committee and staff, I wish to thank Liesl Peters, Clyde Behney, Janice Mehler, Jennifer Bitticks, Jennifer Otten, and Andrea Cohen from the IOM and NRC staffs, who participated in the report review, preproduction, dissemination, and financial management. I would like to acknowledge the assistance of Lauren Strauser in the preparation and analyses of the data from the many cross-sectional studies of noise-induced hearing loss in military personnel that are the basis for Figures 3-3 through 3-6. In addition, the time needed for these analyses, as well as for my writing and editorial duties, would not have been available were it not for a generous release from teaching responsibilities granted to me by Indiana University for the spring 2005 semester. Finally, on behalf of the committee, I wish to express our gratitude to the individuals who made presentations to the committee at its three information-gathering meetings: Mary Schoelen from the Senate Committee on Veterans’ Affairs; COL David Chandler and Douglas Ohlin from the U.S. Army; John Page and Kurt Yankaskas from the U.S. Navy; Maj. Joseph Narrigan and Maj. Robert Pluta from the U.S. Air Force; Al Lillibridge from the U.S. Marine Corps; CDR Wade McConnell from the U.S. Coast Guard; Michael Hodgson, Kyle Dennis, Judy Schafer, and Bradley Flohr from the Department of Veterans Affairs; and veterans Arnold Mathias, Ansell (Mac) MacMillan, Carroll Williams, John Warwick, Rick Weidman, and David Kayal. Our project officer from the Department of Veterans Affairs, Michael Hodgson, provided valuable guidance on the scope of the study as the committee began its work. Also at the Department of Veterans Affairs, Michael Wells responded to several requests for data on veterans receiving disability compensation. Throughout the study, representatives of the military services provided ongoing assistance by responding to numerous requests for infor-

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Noise and Military Service: Implications for Hearing Loss and Tinnitus mation. In particular, we want to acknowledge the assistance of the following individuals in this regard: COL David Chandler, Douglas Ohlin, Kevin Wisniewski, Felix Sachs, and COL Mark Rubertone from the U.S. Army; John Page, Leslie Crowder, Kurt Yankaskas, and Valerie Bjorn from the U.S. Navy; Maj. Robert Pluta and Lt. Col. Wade Weisman from the U.S. Air Force; and CDR Wade McConnell from the U.S. Coast Guard. Larry E. Humes Committee Chair

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Noise and Military Service: Implications for Hearing Loss and Tinnitus Contents     EXECUTIVE SUMMARY   1 1   OVERVIEW OF THE PROBLEM AND INTRODUCTION   15      Charge to the Committee,   16      Acoustics and Noise,   18      The Measurement of Hearing and Tinnitus,   21      Studying the Effects of Noise on Hearing and Tinnitus,   22      Approaches to Hearing Conservation,   25      Evaluating the Strength of Evidence,   27      The Committee’s Report,   31      References,   31 2   NOISE-INDUCED HEARING LOSS   33      Mechanisms and Models of Noise-Induced Hearing Loss,   33      Time Relation between Exposure to Noise and the Development of Hearing Loss and Cochlear Damage,   44      Risk Factors for Noise-Induced Hearing Loss: Individual Differences and Nonacoustic Factors,   47      Estimating Noise-Induced Hearing Loss,   54      References,   64 3   NOISE AND NOISE-INDUCED HEARING LOSS IN THE MILITARY   72      Noise in the Military Environment,   72      Evidence Regarding the Effects of Noise on Hearing Among U.S. Military Personnel,   83      Evidence Based on Average Hearing Thresholds,   89

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Noise and Military Service: Implications for Hearing Loss and Tinnitus      Evidence Based on Variations in Hearing Thresholds Within Groups,   99      Epidemiological Studies of Noise-Induced Hearing Loss in Individuals with Prior Military Service,   109      Findings,   110      References,   111 4   TINNITUS   116      Background,   117      Issues in Studying Tinnitus,   121      Occurrence of Tinnitus,   122      Tinnitus and Noise Exposure,   123      Tinnitus and Hearing Loss,   133      Other Risk Factors,   135      Tinnitus and U.S. Military Personnel,   138      References,   140 5   RESPONDING TO NOISE RISKS: HEARING CONSERVATION PROGRAMS IN THE MILITARY   146      Hearing Conservation Programs,   146      History of Military Hearing Conservation Programs,   147      Assessing the Adequacy of Hearing Conservation Programs,   159      Assessing the Adequacy of Hearing Conservation Programs in the Military,   162      References,   181 6   REPORTS OF AUDIOMETRIC TESTING IN SERVICE MEDICAL RECORDS OF MILITARY VETERANS   190      Study Methods,   191      Results,   194      Compliance with Regulations,   198      References,   200 7   CONCLUSIONS AND COMMENTS   201     APPENDIXES     A   Legislative Language from P.L. 107-330,   209 B   Agendas for Information-Gathering Meetings,   212 C   Definitions,   217 D   Summary Tables on Epidemiological Studies,   223 E   Results from Alternative Analyses of Data on Reports of Audiometric Testing in Service Medical Records,   299 F   Selected Sources of Information on Sound Pressure Levels Measured in and Around Military Systems and Equipment,   301 G   Department of Defense Hearing Conservation Report Forms,   305 H   Biographical Sketches of Committee Members,   315

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Noise and Military Service: Implications for Hearing Loss and Tinnitus Figures, Tables, and Boxes FIGURES 2-1   Semi-schematic drawing of the human ear,   34 2-2   Cross-section of one turn of the spiral-shaped cochlea,   35 2-3   Illustration of a typical noise-notch audiogram,   39 2-4   Drawings of the organ of Corti,   42 2-5   Depiction of the development of the noise-induced permanent threshold shift,   56 2-6   Age-related hearing loss for men (ISO-1999, database A) and hypothetical progression of noise-induced hearing loss with increased length of exposure in years,   61 2-7   Illustrations of the combined effects of aging and noise exposure,   63 3-1   Mean hearing thresholds (left ear) for Army enlisted men serving in 1974 in the infantry, by frequency and length-of-service group,   90 3-2   Mean hearing thresholds (left ear) for enlisted men enrolled in the Navy hearing conservation program, by frequency and age group, 1995–1999,   92 3-3   Average high-frequency thresholds for both ears (arithmetic average of mean values at 3000, 4000, and 6000 Hz in both ears), by age, for selected groups of Army personnel during the 1970s, 1980s, and 1990s,   95 3-4   Average high-frequency thresholds for both ears for selected Navy enlisted personnel in the 1970s and for Navy enlisted men enrolled in the hearing conservation program in 1995–1999,   96

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Noise and Military Service: Implications for Hearing Loss and Tinnitus 3-5   Average high-frequency thresholds for the better ear for selected Marine Corps personnel (officers and enlisted men) in the 1970s and for both ears for enlisted Marine Corps men in the hearing conservation program in 1995–1999,   97 3-6   Average high-frequency thresholds for Air Force personnel enrolled in the hearing conservation program in 1975, 1975–1976, and 1995,   98 3-7   Hearing thresholds (left ear), by frequency, for personnel ages 45–54 years in the Air Force hearing conservation program, 1975–1976,   100 3-8   Distributions of pure-tone thresholds from Air Force personnel enrolled in the hearing conservation program in 1975–1976 and from an unscreened sample of men in the general population at 3000, 4000, and 6000 Hz,   102 3-9   Percentages of each age group, from 18–24 years to 55–64 years, having hearing thresholds greater than 25 dB HL at each of three pure-tone frequencies: 3000 Hz, 4000 Hz, and 6000 Hz,   105 5-1   Time line of major conflicts and milestones in hearing conservation programs,   149 5-2   Comparison of Noise Reduction Ratings published in North America (labeled values based on laboratory tests) to real-world attenuation results derived from 22 studies,   169 5-3   Percentage of Army and Air Force service members enrolled in hearing conservation programs who received annual audiograms, according to the Army Hearing Evaluation Automated Registry System (HEARS) (1989–1998) and the Defense Occupational and Environmental Health Readiness System–Hearing Conservation (DOEHRS-HC) (1999–2003) data repositories,   173 5-4   Percentage of personnel receiving audiometric tests who were identified as showing positive significant threshold shifts (STSs) and permanent threshold shifts (PTSs) (worse hearing) as reported by DOEHRS-HC for the Army, Air Force, Navy, and Marine Corps for 1982–2004,   178 TABLES 1-1   Categories of Hearing Loss and Corresponding Pure-Tone Thresholds for Adults,   21 3-1   Examples of Sound Levels Associated with Military Equipment,   78 3-2   Time Line of Major Conflicts, Milestones in Hearing Conservation Programs, and Hearing Protection Devices,   87

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Noise and Military Service: Implications for Hearing Loss and Tinnitus 4-1   Prevalence of Tinnitus in Adults by Age Group, from Selected Studies,   124 4-2   Percentage of U.S. Military Personnel Completing Post-Deployment Health Assessment Questionnaires Who Reported Tinnitus, by Reported Exposure to Loud Noise During Deployment, 2003–2004,   129 4-3   Percentage of U.S. Military Personnel Completing Post-Deployment Health Assessment Questionnaires Who Reported Any Tinnitus, by Military Service and Reported Exposure to Loud Noise During Deployment, 2003–2004,   130 4-4   Percentage of U.S. Military Personnel Completing Post-Deployment Health Assessment Questionnaires Who Reported Current Tinnitus, by Military Service and Reported Exposure to Loud Noise During Deployment, 2003–2004,   130 4-5   Health and Socioeconomic Factors Associated with a Significant Increase or Decrease in Incidence or Prevalence of Tinnitus,   136 5-1   Criteria for Hearing Conservation Programs,   152 5-2   Available Hearing Protection from World War II to the Present,   166 5-3   Representative Minimum and Maximum Mean Attenuation Values of Well-Fitted Hearing Protectors Under Laboratory Conditions, in dB,   168 5-4   Definitions of Significant Threshold Shift (STS) in the Military Services over Time,   176 6-1   Number of Service Medical Records Reviewed and Abstracted,   195 6-2   Percentages of Service Medical Records with Reports Containing Any Numeric Data from an Audiogram,   195 6-3   Percentages of Service Medical Records with Reports of Audiometric Examinations Within 60 Days of Entry into Active Duty,   196 6-4   Percentages of Service Medical Records with Reports of Audiometric Examinations Within 60 Days of Release from Active Duty,   197 6-5   Percentages of Service Medical Records with Reports of Audiometric Examinations Within 60 Days of Entrance into and Release from Active Duty,   197 D-1   Toluene Exposure as a Risk Factor for Noise-Induced Hearing Loss,   224 D-2   Carbon Monoxide as a Risk Factor for Noise-Induced Hearing Loss in Animals,   232 D-3   Smoking as a Risk Factor for Noise-Induced Hearing Loss,   242 D-4   Progression of Hearing Loss After Noise-Induced Hearing Loss,   250

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Noise and Military Service: Implications for Hearing Loss and Tinnitus D-5   Features of Studies Included in Analysis of Hearing Loss Among Military Personnel,   256 D-6   Studies on Prevalence of Tinnitus and Prevalence of Tinnitus with Hearing Loss,   268 E-1   Percentages of Service Medical Records (95% Confidence Intervals) with Reports of Audiometric Examinations Within 120 Days of Entry into Active Duty,   299 E-2   Percentages of Service Medical Records (95% Confidence Intervals) with Reports of Audiometric Examinations Within 120 Days of Release from Active Duty,   300 E-3   Percentages of Service Medical Records (95% Confidence Intervals) with Reports of Audiometric Examinations Within 120 Days of Entrance into and Release from Active Duty,   300 BOXES ES-1   Compilation of Report Findings,   11 4-1   Sample Questions from Questionnaires Used to Assess the Impact of Tinnitus,   120 6-1   Sampling Frames for Service Eras,   193 6-2   Storage of Service Medical Records,   193