Source: https://expertpages.com/news/sound_recordings_evidence.htm
Timestamp: 2019-04-19 20:57:28+00:00

Document:
FEDERAL RULE OF EVIDENCE 901 (A) PROVIDES in general terms that the requirement of authentication or identification as a condition precedent to the admissibility of evidence is satisfied by proffered proof sufficient to support a finding that the matter in question is what its proponent claims it to be. A foundation for authentication of sound recordings was established in the federal courts in United States v. McKeever,*1* and upheld in cases such as United States v. McMillan.*2* In McMillan the court ruled that where a government agent testified that he heard the voice .of an informant at all times when he was making a recording of a telephone conversation, that this part of the conversation was accurate, and that immediately after the telephone calls were completed, a tape was replayed by the agent in the informant's presence to verify that the conversation had in fact been recorded and that the instruments were operating correctly, it was sufficiently established that the recordings were true and accurate as a basis for their admission in evidence.
OVER THE PAST 35 YEARS, ATTORNEYS HAVE UTILIZED THE basic process set forth in McMillan to create cases for admission of tapes or, on the opposition side, to deny admission of tape evidence.
Competency of the operator:today most people know how to operate a tape recorder so this step is almost automatic. In United States v. McCowan,*8* the agent merely testified that he learned how to use the recorder on the day he made the tapes. The fact that he successfully made the recordings satisfied the competency requirement.
"Recent cases have developed more flexible standards for the admission of tape recorded conversations. The most important criterion for admission is that the tapes accurately reflect the conversation which they purport to record .... This evidence may be circumstantial or direct, real or testimonial, and need not conform to any particular mode." Therefore, according to the more liberal admission rulings, a tape recording may be admitted into evidence if a proper chain of custody is proven. Or, if the chain is not strong enough, the proponent of the tape may submit it to a qualified forensic expert for authentication. In United States v. King,*18* the United States Court of Appeals for the Ninth Circuit characterized the elements of the process as "useful, but not dispositive guidelines for determining when a proper foundation for the introduction of sound recordings has been made." The Ninth Circuit said that the trial court, in the exercise of its discretion, must be satisfied that the recording is accurate, authentic and generally trustworthy.
WHEN AN AUDIO TAPE IS SUSPECTED OF HAVING BEEN TAMPERED with, it may be forwarded to a qualified forensic audio specialist for authentication. Prosecutors often request investigation of deficiencies in the previously mentioned process.
Differences between the content of the tape and testimony of what was said.
Most often, however, a forensic expert is contacted when the tape is believed to have been altered or tampered with. Due to the nature of the allegations surrounding tampering issues, the examiner will requirements specific items from the party.
A derailed statement from the person or persons who made the recording, describing exactly how it was produced and the conditions that existed at the time, such as: 1. Power source, including a portable generator or drycell batteries; 2. Input, such as telephone, radio frequency transmitter/receiver, miniature microphone, etc.; 3. Environment, such as telephone transmission line, restaurant, apartment, street, etc.;4. Background noises, such as television, radio, unrelated conversations, computer games, etc.; 5. Foreground information, such as number of individuals involved in the conversation, general topics of discussion, closeness to microphone, etc.;6. Magnetic tape, such as brand, format, when purchased, whether previously used;7. Recorder operation, such as number of times turned on and off in the record mode, type of keyboard or remote operations for all known recorded events, use of voice-activated features, etc.
Extraneous voices: background voices which at times appear to be as near as the primary voices (these can, at times, even block the primary voices).
CERTAIN TECHNICAL DEFINITIONS SHOULD BE UNDERSTOOD by prosecutors and others in considering the technical process of examining sound recordings. They include the ones listed below.
Synthesis: the adding of words or sounds by artificial means or impersonation.
A FORENSIC EXPERT IS TRAINED to detect falsifications and to authenticate sound recordings. The expert correlates his observations of anomalies with machine functions to interpret events in the following ways.
Critical listening: this involves the use of human analytical capabilities to locate anomalies. The forensic expert listens with proper headphones to the original tape using high-quality analytical equipment. He first performs a preliminary overview of the original tape and notes events, including starts, stops, speed fluctuations, and other variations requiring further investigation. He then examines recorded events and categorizes them as environmental or non-environmental. After examining recorded events, the expert analyzes background sounds. He listens for abnormal changes, absences or the presence of environmental sound. The final phase of critical listening is an extensive audit of the foreground information. He concentrates on voices, conversations and other audible sounds. Here anomalies include sudden changes in a person's voice, abrupt unexplained topic change or strong foreground interruptions indicative of obscuration. The initial forensic process of critical listening provides foundation and direction for later intensive instrumental tests.
Physical inspection: the forensic expert next inspects for tampering with thorough visual inspection of the tape itself. She inspects the housing for pry marks, welding, size, label and date, consistent with the alleged recording date. She also measures the tape and assures that the splicing of the magnetic tape to the leader is consistent with a normal manufacturing process. Any other splices are noted as possible alterations.
Magnetic development: direct visual observation of the "developed" tape is conducted to find track widths, the type of recorder used and the presence or absence of residual speech signals.
Spectrum analysis: specialized computer equipment and programs to produce a visual interpretation of a frequency- versus-amplitude and frequency-versus-amplitude-versus-time displays. This allows the expert to view the entire spectrum or to zoom in on an area of particular interest thereby helping to characterize the acoustic quality of anomalies and identify their source.
Waveform analysis: a computer generated display representing time-versus-amplitude of recorded sounds in graphic form. With such analysis the expert can often measure signal return time, which reveals how long a recorder had been turned off. He can identify record- mode events, including the measurement of record-to- erase-head distance, determination of the spacing between gaps in multiple-gap erase heads and inspection of the signature shape and spacing of various record event signals.
Recorder performance: various electrical and mechanical measurements of standard and modified recorders for use in finding possible origins of buzz sounds, hum, etc.
IN ORDER TO SUBMIT SOUND RECORDINGS AS EVIDENCE IN court, a prosecutor or other attorney must establish that the tape is an authentic representation of the conversation it is said to record. The traditional method of establishing authenticity involves maintaining a chain of custody which logs all persons, times and locations concerned in the creation of the tape. Then, the tape must be officially sealed and stored to complete a proper chain of custody. However, even if this procedure is strictly observed, there may still be challenges to the tape's authenticity.
[space]The recording may contain inconsistencies suggestive of tampering. In such cases, a prosecutor may consult a qualified forensic examiner to inspect the tape. The examiner would initially listen critically for signs such as gaps, transients fades, equipment sounds or extraneous voices which indicate tampering. Then she would utilize other methods like physical inspection, magnetic development, spectrum analysis and waveform analysis to discover anomalies.
It is relatively easy to change the content of a recording by deleting words or sections, by obscuring meaning with over-recorded sounds, or by transforming context through rearrangement of selected phrases or by adding additional words through synthesis. Nevertheless, falsifications normally leave detectable magnetic and waveform acoustic signatures which can lead to forensic individualization of the evidential recorders and tapes.
1 United States v. McKeever, 169 E Supp. 426, 430 (S.D.N.Y. 1958), rev'd on other grounds, 271 E2d 669 (2d Cir. 1959).
2 United States v. McMillan, 508 E2d I01,104 (8th Cir. 1974), cert. denied, 42 1 U.S. 916 (1975); see also United States v. Kandiel, 865 E2d 967,973-974 (8th Cir. 1988), cert. denied, 487 U.S. 1210 (1988); Todisco v. United States, 298 E2d 208 (9th Cir. 1962).
3 United States v. Kandiel, 865 E2d 967,973-974 (8th Cir. 1988),cert. denied, 487 U.S. 1210 (1988).
4 Kandiel, 865 E2d at 974.
5 McMillan, 508 E2d at 104.
7 United States v. Moss, 591 E2d 428, 433 (8th Cir. 1979); United States v. McCowan, 706 E2d 863 (8th Cir. 1983).
8 McCowan, 706 E2d at 863.
9 Zenith Radio Corp. v. Matsushita Electrical Industries Co., 505 E Supp. 1190 (E.D. Pa. 1980), and Finance Co. of America v. Bankamerica Corp., 493 E Supp. 895 (D.C. Md. 1980).
10 Gass v. United States, 416 E2d 767,770 (D.C. Cir. 1969); United States v. Haldeman, 559 E2d 31 (D.C. Cir. 1976).
11 United States v. Faurote, 749 E2d 40 (7th Cir. 1984).
12 United States v. Craig, 573 E2d 455 (7th Cir. 1977), cert. denied, 439 U.S. 820 (1978).
13 United States v. Rizzo, 492 E2d 443 (2d Cir. 1974), cert. denied, 417 U.S. 944 (1974); United States v. Bonanno, 487 E2d 654 (2d Cir. 1973); United States v. Hughes, 658 E2d 317 (5th Cir. 1981).
14 United States v. White, 401 U.S. 745 (1971); United States v. Bonanno, 487 E2d 654 (2d Cir. 1973); United States v. Bishton, 463 E2d 887 (D.C. Cir. 1972); United States v. Quintana, 457 E2d 874 (10th Cir. 1972), cert. denied, 409 U.S. 877 (1972); United States v. Holmes, 452 E2d 249 (7th Cir. 1971), cert. denied, 405 U.S. 1016 (1972).
15 United States v. West, 948 E2d 1042 (6th Cir. 1991); People v. Rogers, 543 N.E.2d 300 (Ill. 1989); State v. Rodfiguez, 583 N.E.2d 795 and. 1972).
16 United States v. Enright, 579 E2d 980 (6th Cir. 1978); United States v. Gordon, 688 E2d 42 (8th Cir. 1982).
17 United States v. Traficant, 558 E Supp. 996, 1002 (N.D. Ohio, 1983).

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