National Academy of Sciences (NAS)

Report of the Committee on
Ballistic Acoustics

REPORT OF THE
COMMITTEE ON BALLISTIC ACOUSTICS

COMMISION ON PHYSICAL SCIENCES,
MATHEMATICS, AND RESOURCES

NATIONAL RESEARCH COUNCIL

NATIONAL ACADEMY PRESS
Washington, DC 1982

 

TABLE OF CONTENTS

EXECUTIVE SUMMARY

I. INTRODUCTION AND OVERVIEW

II. DESCRIPTION OF STUDIES BY BRSW AND WA

III. EVALUATION OF BRSW AND WA METHODOLOGIES AND CONCLUSIONS

IV. TIMING EVIDENCE FROM MATCHING FEATURES

IV-1. Sound Spectrograms

IV-2. Analysis of Sound Spectrograms of "Hold Everything"

IV-3. Timing of Channel I and Channel II Events

IV-4. Possibility of Superposed Recordings

V. EVALUATION OF THE FBI REPORT

VI. POSSIBLE FURTHER STUDIES

VII. CONCLUSIONS

APPENDIXES

APPENDIX A: CRITICISMS OF PROBABILITY CALCULATIONS

A-1. Criticism of BRSW Probabilities of 0.88, 0.88, 0.50 and 0.75

A-2. Criticism of BRSW Certainty that Microphone Detected Sound of Gunfire

A-3. Criticism of BRSW/WA Probability of 0.95 for Shot from Grassy Knoll

APPENDIX B: ANALYSES OF SOUND SPECTROGRAMS OF "HOLD EVERYTHING . . ."

B-1. Time and Frequency Analysis

B-2. Measurements of Easily Identified Frequency Ratios on Sound Spectrograms

B-3. Alternative Time and Frequency Analyses of Sound Spectrograms

B-4. Digital Calculations of Cross Correlation Between Channel and Channel II

APPENDIX C: TIMING OF CHANNEL I AND II EVENTS

C-1. Analysis of the Bowles Tapes

C-2. Analysis of Tapes Made Directly from Original Records

APPENDIX D: POSSIBILITY OF SUPERPOSED RECORDINGS

APPENDIX E: SIREN SOUNDS

APPENDIX F: POSSIBLE FURTHER STUDIES

REFERENCES

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