National Academies Press: OpenBook

Report of the Committee on Ballistic Acoustics (1982)

Chapter: Front Matter

Suggested Citation:"Front Matter." National Research Council. 1982. Report of the Committee on Ballistic Acoustics. Washington, DC: The National Academies Press. doi: 10.17226/10264.
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Suggested Citation:"Front Matter." National Research Council. 1982. Report of the Committee on Ballistic Acoustics. Washington, DC: The National Academies Press. doi: 10.17226/10264.
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Suggested Citation:"Front Matter." National Research Council. 1982. Report of the Committee on Ballistic Acoustics. Washington, DC: The National Academies Press. doi: 10.17226/10264.
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Suggested Citation:"Front Matter." National Research Council. 1982. Report of the Committee on Ballistic Acoustics. Washington, DC: The National Academies Press. doi: 10.17226/10264.
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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please i 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 report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The National Research Council was established 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 of advising the federal government. The Council operates in accordance with general policies determined by the Academy under the authority of its congressional charter of 1863, which establishes the Academy as a private, nonprofit, self-governing agency of both the National Academy of Sciences and the National Academy of Engineering in the conduct of their services to the government, the public, and the scientific and engineering communities. It is administered jointly by both Academies and the Institute of Medicine. The National Academy of Engineering and the Institute of Medicine were established in 1964 and 1970, respectively, under the charter of the National Academy of Sciences. Available in limited number from Commission on Physical Sciences, Mathematics, and Resources 2101 Constitution Avenue Washington, D.C. 20418 use the print version of this publication as the authoritative version for attribution.

About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please ii COMMITTEE ON BALLISTIC ACOUSTICS Norman F.Ramsey, Harvard University, Chairman Luis W.Alvarez, Lawrence Berkeley Laboratory, University of California Herman Chernoff, Massachusetts Institute of Technology Robert H.Dicke, Princeton University Jerome I.Elkind, Xerox Palo Alto Research Center John C.Feggeler, Bell Telephone Laboratories, Holmdel, New Jersey Richard L.Garwin, Thomas J.Watson Research Center, IBM Corporation, and Adjunct Professor of Physics, Columbia University Paul Horowitz, Harvard University Alfred Johnson, Bureau of Alcohol, Tobacco, and Firearms, National Laboratory Center, Department of the Treasury Robert A.Phinney, Princeton University Charles Rader, Lincoln Laboratory, Massachusetts Institute of Technology F.Williams Sarles, Trisolar Corporation, Bedford, Massachusetts (The views expressed in this report do not necessarily represent those of the home institutions of the participants.) Staff C.K.Reed, Senior Advisor, Commission on Physical Sciences, Mathematics, and Resources Bertita E.Compton, Special Assistant, Commission on Physical Sciences, Mathematics, and Resources use the print version of this publication as the authoritative version for attribution.

About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please TABLE OF CONTENTS iii TABLE OF CONTENTS PAGE EXECUTIVE SUMMARY 1 I. INTRODUCTION AND OVERVIEW 3 II. DESCRIPTION OF STUDIES BY BRSW AND WA 8 III. EVALUATION OF BRSW AND WA METHODOLOGIES AND CONCLUSIONS 12 IV. TIMING EVIDENCE FROM MATCHING FEATURES 18 IV-1. Sound Spectrograms 20 IV-2. Analysis of Sound Spectrograms of “Hold Everything” 23 IV-3. Timing of Channel I and Channel II Events 27 IV-4. Possibility of Superposed Recordings 30 V. EVALUATION OF THE FBI REPORT 32 VI. POSSIBLE FURTHER STUDIES 33 VII. CONCLUSIONS 34 APPENDIXES 35 APPENDIX A: CRITICISMS OF PROBABILITY CALCULATIONS 35 A-1. Criticism of BRSW Probabilities of 0.88, 0.88, 0.50 and 0.75 35 use the print version of this publication as the authoritative version for attribution. A-2. Criticism of BRSW Certainty that Microphone Detected Sound of Gunfire 37 A-3. Criticism of BRSW/WA Probability of 0.95 for Shot from Grassy Knoll 38 APPENDIX B: ANALYSES OF SOUND SPECTROGRAMS OF “HOLD EVERYTHING...” 41 B-1. Time and Frequency Analysis 41 B-2. Measurements of Easily Identified Frequency Ratios on Sound Spectrograms 49 B-3. Alternative Time and Frequency Analyses of Sound Spectrograms 52 B-4. Digital Calculations of Cross Correlation Between Channel I and Channel II 57

About this PDF file: This new digital representation of the original work has been recomposed from XML files created from the original paper book, not from the original typesetting files. Page breaks are true to the original; line lengths, word breaks, heading styles, and other typesetting-specific formatting, however, cannot be retained, and some typographic errors may have been accidentally inserted. Please use the print version of this publication as the authoritative version for attribution. APPENDIX E: APPENDIX D: APPENDIX F: C-2. C-1. APPENDIX C: TABLE OF CONTENTS REFERENCES SIREN SOUNDS Analysis of the Bowles Tapes POSSIBLE FURTHER STUDIES TIMING OF CHANNEL I AND II EVENTS POSSIBILITY OF SUPERPOSED RECORDINGS Analysis of Tapes Made Directly from Original Records 96 92 89 81 67 60 60 iv

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At the time of the assassination of President Kennedy, the Dallas police recorded sounds from an open microphone; these sounds have been previously analyzed by two research groups at the request of the House Select Committee on Assassinations. Both groups concluded with 95% probability that the recordings contained acoustic impulses which provide evidence for the existence of a shot from the grassy knoll area of Dealey Plaza. On the basis of these results and since shots definitely were fired from the Texas School Book Depository, the House Committee concluded that "scientific acoustical evidence establishes a high probability that two gunmen fired at President John F. Kennedy."

Report of the Committee on Ballistic Acoustics studied these reports and the Dallas Police recordings on which they are based. This book reviews the methodology employed in the evaluations of the recorded acoustic data and of the conclusions about the existence of a shot from the grassy knoll. According to this report, the acoustic analyses do not demonstrate that there was a grassy knoll shot, and in particular there is no acoustic basis for the claim of 95% probability of such a shot. The acoustic impulses attributed to gunshots were recorded about one minute after the President had been shot and the motorcade had been instructed to go to the hospital. Therefore, reliable acoustic data do not support a conclusion that there was a second gunman.

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