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Audio Recordings: Evidence, Experts and Technology

Gruber, J. S., Poza, F. and Pellicano, A. J.
1993: 48 Am Jur Trials, Lawyers Cooperative Publishing.


TABLE OF CONTENTS


I. PREFATORY COMMENTS
A. Introduction
。・1. In General
。・2. Increase in Audio Recordings
。・3. Relaxation of Evidentiary Standards
。・4. Increasing Technological Ability to Edit and Falsify Evidence
。・5. Growing Specialty of Forensic Audio
B. Scope of Article
。・6. In general
。・7. Audio Technology
。・8. Evidentiary Standards
。・9. Forensic Audio
C. Terminology
。・10. In General
。・11. Glossary of Technical and Evidentiary Audio Terms
II. BASICS OF SOUND AND AUIDIO RECORDING
A. Sound, Speech, and Sound Waves
。・12. In General
。・13. Characteristics of Sound Waves
。・14. Frequency
。・15. Harmonic Structure
。・16. Amplitude
B. Theory of Audio Recording
。・17. In General
。・18. Transducers
。・19. Storage Mechanisms
。・20. The Recording Process
C. Evolution of Audio Recording Devices
。・21. In General
。・22. Overview
。・23. Phonographic Recording
。・24. Magnetic Recording
。・25. Digital Recording
。・26. Types of Audio Recording Devices and Storage Mediums
D. Auxiliary Equipment
。・27. In General
。・28. Microphone
。・29. Amplifier
。・30. Speakers
III. ANALOG AUDIO RECORDERS
A. Concept Behind Analog Recording
。・31. In General
。・32. Strengths of Analog Recording
。・33. Disadvantages
B. Analog Recorders Using Magnetic Tape Storage Medium
。・34. In General
。・35. Types of Analog Magnetic Tape Recorders
。・36. Magnetic Tape
。・37. Components and Functioning of Typical Magnetic Tape Recorder
。・38. Erase, Record, and Playback Heads
C. Analog Recorders Using Other Storage Mediums
。・39. Wire
。・40. Non-Magnetic Storage Medium
IV. DIGITAL AUDIO RECORDERS
A. Concept Behind Digital Recording
。・41. In General
。・42. Sampling and Quantizing
。・43. Processing, Recording, and Playback
。・44. Comparison to Analog Recording
B. Digital Recorders Using Magnetic Tape Storage Medium
。・45. In General
。・46. Digital Audiotape (DAT) Recorders
。・47. Digital Compact Cassette (DCC) Recorders
。・48. Stationary Head Recorders
。・49. Camcorders
。・50. Backup Storage Mediums
C. Digital Recorders Using Tapeless Magnetic Storage Medium (Computer-Recorders)
1. In General
。・51. Tapeless Digital Recorder
。・52. Advantages of Using Computer-Recorders
。・53. Samplers
。・54. Microcomputers
。・55. Digital Audio Workstationis
2. Tapeless Magnetic Storage Mediums
。・56. In General
。・57. Floppy Disks
。・58. Hard Disks
。・59. Removable Cartridges
。・60. Floptical Disks
。・61. Magneto-Optical Cartridges
D. Digital Recorders Using Non-Magnetic Storage Medium
。・62. In General
。・63. Digital Recorders Using Semi-Conductor Memory Chips
。・64. Digital Rerorders Using Optical, Laser-Based, Storage---Generally
。・65. ---WORM Disc
。・66. ---MiniDisec
。・67. ---Recordable Disc
V. FUTURE OF AUDIO RECORDIING DEVICES AND STORAGE MEDIUMS
A. Trends With Imlications for the Legal Practitioner
。・68. In General
。・69. Digitization
。・70. Shift Away froin Magnetic Tape
。・71. Manipulability of Recordings
。・72. Miniaturization
。・73. Proliferation of Formats
B. Growth of Related Technologies
。・74. In General
。・75. Digital Signal Processing
VI. USES OF AUDIO RECORDINGS IN THE LEGAL SYSTEM
A. Current Evidentiary Usage
。・76. In General
。・77. Categorization According to Temporal Relationship to Occurrence
。・78. Checklist of Functional Uses During Trials or Hearings---Generally
。・79. ---Criminal Cases
。・80. ---Civil Proceedings
B. Miscellaneous Uses
。・81. In General
。・82. Recording Depositions
。・83. Recording Trials
C. Pros and Cons of Audio Recording as Evidence
。・84. In General
。・85. Persuasive Power of Audio Recordings
。・86. Comparison to Videotape Evidence
。・87. Overall Impaot on the Legal System
VII. OVERVIEW OF EDITING, FALSIFICATION, AND FABRICATION
A. Terminology and Conceptual Relationships
。・88. In General
。・89. Editing
。・90. Intentional Versus Accidental "Falsification"
。・91. Alteration
。・92. Tampering
。・93. Fabrication
B. Ability to Falsify and Detect Falsification
。・94. In General
。・95. Historical Advancements in Editing Capabilities
。・96. Potential "Falsifiers"---Generally
。・97, ---Forensic Audio Specialist
。・98. ---Hobbyists
。・99. Detectability---Generally
。・100. ---Necessary Skills and Resources
。・101, ---Attorney's Review of Recording
C. Techniques
。・102. In General
。・103. Contemporaneous Editing
。・104. Editing Affecting Source Recording
。・105. Editing Not Affecting Source Recording
D. Practical and Legal Ramifications
。・106. In General
。・107. Categorization of Different Types of Editing
。・108. Categories of Editing and Impact on Admissibility
。・109. When to Challenge Admissibility
VIII. EDITING CONTEMPORANEOUS WITH RECORDING

。・110. Recordist's Subjective Choices
。・111. Inherent Distortions
。・112. Checklist of Distortional Effects
。・113. Record Event and Tape Transport Signatures
。・114. Significance of Prmnce of Record Event Signature
IX. EDITING THAT PHYSICALLY AFFECTS THE SOURCE RECORDING
A. Splicing of Tapes.
。・115. In general
。・116. Advantages and Disadvantages of Splicing
。・117. Mechanics of Splicing
。・118. Detection of Splicing
B. Over-Recording
。・119. In general
。・120. Input Method
。・121. Sound-on-Sound Recording
。・122. Record-Erasure
。・123. Insert-Edits, Types of Sources, and Record Events
。・124. Dewtion of Over-Recording
C. Tape Erasure
。・125. In General
。・126. Detection
。・127. Recovery and Reconstitution-Generally
。・128. ---Limitations
X. EDITING THAT DOES NOT PHYSICALLY AFFECT SOURCE RECORDING
A. Re-Recording (Dubbing)
。・129. In General
。・130. Advantages, Disadvantages, and Importance of Re-Recording
。・131. Mechanics and Detectability of Analog Re-Recording
。・132. Examples of Re-Recording
B. Potentially Undetectable Digital Re-Recording
。・133. In General
。・134. Mechanics of Digital Re-Recording
。・135. Subsequent Removal of Record Event Signatures by Computer-Recorder
C. Synchronization
。・36. In General
。・37. Time Code
。・38. Security Coding
D. Enhancement Of Recordings
。・139. In General
。・140. Efficacy of Enhancement Techniques and Equipment
。・141. Noise, Speech, and Relevant Frequency Spectra
。・142. Classical Filtering-Generally
。・143. -Specific Uses and Efficacy
。・144. Computer-Based Filtering Systems-Generally
。・145. ---Specific Uses and Efficacy
。・146. Other Enhancement Techniques
XI. FABRICATION OF AUDIO RECORDINGS
A. Types Of Speech Fabrication
。・147. In General
。・148. Impersonation
。・149. Complex Re-Recording
。・150. Analysis and Resynthesis (Vocoding)
。・151. Speech Synthesis by Joining ("Concatenating") Pre-recorded Speech Components-Generally
。・152. ---Operation of Concatenation Systems
。・153. ---Linking Individual Speech Units
。・154. Speech Synthesis by Rule-Generally
。・155. ---Operation of Synthesis-by-Rule Systems
。・156. ---Flexibility of Existing Commercial System
。・157. Comparison of Concatenation and Synthesis by Rule
B. Detectability Of And Advances In Speech Fabrication Methods
。・158. In General
。・159. Latest Advances
。・160. Likelihood of Undetectable Fabrication
。・161. Current Status of the Different Fabrication Methods
。・162. Obstacles to Producing Undetectable Fabricated Speech
。・163. Predictions for the Future of Fabrication Technologies
XII. CONSULTING THE FORENSIC AUDIO EXPERT
A. Emerging Discipline Of Forensic Audio
。・164. In General
。・165. Difficulties Facing Acceptance of Forensic Audio as Recognized Discipline
。・166. Current and Future Status of Forensic Audio
。・167. Effect of Shift to Digital Recording and Editing
B. Determining Whether To Consult Forensic Audio Expert
。・168. In General
。・169. General Advantages of Consulting a Forensic Audio Expert
。・170. General Disadvantages of Consulting a Forensic Audio Expert
。・171. Checklist of Case-Specific Factors in Favor of Consulting a Forensic Audio Expert
。・172. Use of Multiple Experts
C. Chooslng The Forensic Audio Expert

1. In General
。・173. Choosing the Audio Expert
。・174. Locating the Expert
2. Evaluating the Expert
。・175. Conflicts Among Experts
。・176. Educational, Training, and Other Professional Qualifications
。・177. Demeanor
。・178. Other Considerations
D. Expert's Ethics
。・179. In General
。・180. Scientific Impartiality and Objectivity
。・181. Expert's Contact with Those Involved in Case
。・182. Expert's Potential Overselling of Services
。・183. Expert's Recognition of Limits to Own Knowledge and Conclusions
XIII. PRACTICAL AND EVIDENTIARY CONSIDERATIONS WHEN USING A FORENSIC AUDIO EXPERT
A. Qualifying The Expert
。・184. In General
。・185. Approaches to Voir Dire
B. Expert's Proper Role: Technical "Authentication" Versus Legal Authentication
。・186. In General
。・187. Importance of Distinction
。・188. Demonstration of Consistency With Purported Protocol
。・189. Necessity for Terminological Clarity
C. Evidentiary And Scientific Limitations On Expert's Testimony
1. In General
。・190. Overview
。・191. Limitations Prescribed by Evidentiary Rules
。・192. Scientific Limitations
2. The "Fiye" Test
。・193. In General
。・194. Relevance to Forensic Audio
。・195. Particular Lines of Questioning Relating to Anomalies in Examined Recording
。・196. Chances for Successful Rule 702-Based Challenge
D. Foundational Checklists For Expert Forensic Audio Testimony
。・197. In General
。・198. Foundation for Instrumental Scientific Evidence
。・199. Foundation for Non-Instrumental Scientific Evidence
E. Other Considerations
。・200. Right to Have Recording Examined by Expert
。・201. Expert's Notes and Report
。・202. Expert's Creation and Use of Demonstrative Evidence
XIV. TECHNICAL "AUTHENTICATION" BY FORENSIC AUDIO EXPERT
A. Overview
。・203. In General
。・204. "General Questions"
。・205. Technical "Authentication" Activities Checklists---Generally
。・206. ---Information Gathering from Outside Sources
。・207. ---Evidence Handling
。・208. ---Physical Inspection of Recording and Recorder
。・209. ---Aural Review of. Recording
。・210. ---Instrumental Analyses of Recording
B. Variations And Commonalities In Experts' Protocols
。・211. In General
。・212. Reasons for Differences
。・213. Illustrative Technical "Authentication" Protocols
。・214. Exhaustive Versus Cost-Effective Protocols
C. Record Interruption Signatures
。・15. In General
。・216. Significance of Record Event Signatures
。・217. Varieties and Nature of Record Event Signatures
。・218. Lack of Scientific Data Signatures' Uniqueness and Consistency
。・219. Detection and identification of Signatures
。・220. Addition and Detection of Apparently Original Signatures
D. Acoustic Anomalies
。・221. In General
。・222. Possible Causes
。・223. Significance
E. Obtaining And Examining Original Recording And Recorder
。・224. In General
。・225. Importance of Examining Original Recording
。・226. Access issues
。・227. Determining Originality
F. Non-Instrumental Activities And Techniques
。・228. Information Gathering
。・229. Evidence Handling
。・230. Physical Inspection-Recording
。・231. -Recorder
。・232. Critical Listening-Generally
。・233. ---Methods
。・234. ---Maximizing Information Obtained
G. Instrumental Techniques

1. Wavefonn Analysis
。・235. In General
。・236. Equipment Used to Produce Waveforms
。・237. Audio Recorder Used to Play Back Recording
。・238. Production of Known Exemplars
。・239. Illustrations of Waveform Signatures
2. Magnetic Development
。・240. In General
。・241. Uses of Magnetic Development
。・242. Advantages and Disadvantages of Using Magnetic Development
。・243. Methodology
。・244. Illustrations of Magnetic Development
3. Spectrographic analysis
。・245. In General
。・246. Sound Spectrogram Analysis
。・247. FFT Analysis
XV. ADMISSIBILITY OF AUDIO EVIDENCE
A. In General
。・248. Historical Background
。・249. Widespread Belief in Fundamental Reliability of Sound Recordings
。・250. Effect of Recognition of Possibility of Falsification
。・251. Evidentiary Classifications of Audio Evidence
。・252. Criminal Versus Non-Criminal Proceedings
。・253. Summary of Requisites for Admissibility
。・254. Broad Discretion of Trial Judge
B. Materiality, Relevance, And Competency
。・255. In General
。・256. Competence Issues
。・257. Probative Value Versus Prejudicial Effects: Rule 403 and General Usefulness to Trier of Fact
。・258. Inclusion of Irrelevant, Incompetent, or Prejudicial Material
C. Indistinct, Incomplete, Or Inaudible Recordings
。・259. In General
。・260. Supplementation of Recordings with Transcripts
。・261. Practical Considerations
D. Miscellaneous Objections To Admissibility
。・262. Hearsay
。・263. Cumulative Evidence
。・264. Best Evidence
。・265. Privileged Communications
。・266. Rule 106 Completeness Doctrine
。・267. "Self-Serving" Exculpatory Statements
XVI. AUTHENTICATION AND LAYING OF FOUNDATION
A. In General
。・268. Necessity of Laying Foundation and Authenticating Recording
。・269. Traditional "Seven-Pronged" Predicate
。・270. Flexibility and Trends in Modern Foundation Requirements
。・271. Foundational Witnesses
。・272. Minimal Sufficient Foundation
。・273. Burden of Proof
。・274. Presumption of "Official Regularity"
。・275. Determinations
。・276. Judicial Notice
。・277. Foundation Checklist
B. Specific Foundational Criteria
。・278. Authenticity (Genuineness, Trustworthiness)
。・279. Accuracy (No Changes, Additions, or Deletions)
。・280. Correct and Fair Representation (Volume Levels)
。・281. Competency and Qualifications of Equipment Operator
。・282. Capability of Machine
。・283. Identification of Speakers
。・284. Voice Identification
。・285. Acoustic Identification
。・286. Chain of Custody
。・287. Testimony Not Coerced
。・288. Interval Before Subsequent Playback
C. Re-Recordings
。・289. In General
。・290. Re-recordings Offered in Place of Lost or Unavailable Original Recording
。・291. Enhanced Re-recordings
。・292. Composite Re-recordings
XVII. PRACTICAL TRIAL CONSIDERATIONS

。・293. In Camera Review
。・294. Stipulated Acceptance
。・295. Checklist of Steps for Admission of Audio Recording Into Evidence
。・296. Strategic Importance of Timely and Specific Challenges to Admissibility
。・297. Provision of Playback Equipment for Courtroom Use
。・298. Use of Transcripts
。・299. Cautionary Jury Instructions

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