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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.
In United States v. Kandiel
,*3* the court ruled that any question concerning
the credibility of a witness who identifies voices on a tape recording admitted
into evidence simply goes to the weight which the jury accords the evidence, not
its admissibility. Referring to McMillan
the court said:
Applying [the McMillan case], we conclude that the government laid a
proper foundation for introduction of the two cassette tapes into evidence.
The tapes were found at appellant's home. Ahmed Kandiel [defendant's brother]
testified that the tapes were made in Egypt and sent to appellant by their mother
and father while Ahmed was living with appellant. The contents of the tape recordings
have numerous references to people, places and activities that were corroborative
of other testimony in the record. We believe the government has offered sufficient
circumstantial evidence to establish the prima facie authenticity and correctness
of the tapes. Furthermore we find that the government sufficiently established
the identity of the speakers through the testimony of Ahmed Kandiel. Appellant's
argument that Ahmed's credibility was suspect, and that therefore his testimony
was insufficient to establish foundation for the admission of the tapes is with
out merit. Identification of a voice, whether heard firsthand or through mechanical
or electronic transmission or recording, may be made "by opinion based upon
hearing the voice at any time under circumstances connecting it with the alleged
speaker." Fed. R. Evid. 901(b)(5). Any question concerning the credibility of
the identifying witness simply goes to the weight the jury accords this evidence,
not to its admissibility. United States v. Kirk, 534 E2d 1262, 1277 (8th Cir.
1976), cert. denied, 433 U.S. 907, 97 S. Ct. 2971, 53 L. Ed. 2d 1091 (1977).
Our review of the record convinces us that the district court did not abuse
its discretion in finding that proper foundation was laid for admitting the
tapes. See United States v. Johnson, 767 E2d 1259, 1271 (8th Cir. 1985).*4*The cases are, therefore, now in general agreement as to what
constitutes a proper foundation for the admission of a sound recording and indicate
a reasonably strict adherence to the rules prescribed for testing admissibility
of recordings, as set forth in McMillan.*5*
These rules can be summarized as
- The recording device must have been capable of taking the
conversation now offered in evidence
- The operator of the device must be competent to operate
- The recording must be authentic and correct
- Changes, additions or deletions have not been made in the
- The recording must have been preserved in a manner that
is shown to the court
- The speakers must be identified
- The conversation elicited was made voluntarily and in good faith, without any kind of inducement.*6*
THE BASIC PROCESS
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.
process involves the following elements:
- Capability of the recording device:this first
requisite may be fulfilled simply. The very existence of the tape recording
proves that the recording device was functioning and capable of duplicating
- 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.
- Authenticity and correctness of the recording:authentication is satisfied by evidence sufficient to support a finding that the matter in question is "what its proponent claims,*9* as decreed in Federal Rule of
Evidence 901. The standard for correctness of a recording is whether "the
possibility of misidentification and adulteration [is] eliminated, not
absolutely, but as a matter of reasonable probability."*10*
- Preservation of the recording with no additions,
deletions or changes:an aural overview of the tape allows the court to
hear signs (i.e., gaps) which might indicate tampering. If there exist
signs of tampering, a forensic expert is often consulted. If there are no
signs of tampering, a proper chain of custody documentation may suffice.*11*
- Chain of custody:
this fifth step has created
stumbling blocks for proponents of admissibility. The proponent for the tape's
admittance can assure the court that the item offered as evidence is
substantially the same as it was originally by documenting its "chain of
custody." A proper chain of custody begins with consecutively numbered and
dated tapes. Careful logs are then kept which note the time of particular
conversations and the locations on the tapes at the time of occurrence. These
evidence tapes are sealed and stored in separate envelopes and appropriate
chain of custody records are maintained by the evidence custodian. *12*
- Identification of the speakers:Federal Rule of
Evidence 901(b)(5) states that: "Voice identification is adequate if made by a
witness having sufficient familiarity with the speaker's voice." The rule goes
on to clarify that familiarity may be obtained previous to or after listening
to the recorded voice. This standard for voice identification has been upheld
in cases such as United States v. Rizzo, United States v.
Bonanno, and United States v. Hughes)*13*
- Voluntary elicitation of the recorded
conversation:as long as one participant in the conversation is aware
that he is being recorded, the tape fulfills this final requirement. This
means that a defendant's Fourth Amendment rights are not violated when the
conversation is electronically monitored by a government agent with consent of
the government informant in the investigation.*14*
ADMISSIBILITY OF INAUDIBLE SOUND
IT IS A GENERAL RULE THAT A sound recording is admissible
unless the inaudible portions or omissions are so substantial as to render the
recording as a whole untrustworthy as evidence.*15* It has further been established that the question of
admissibility of audible portions of tape recordings, when certain portions
were inaudible, was properly addressed to the discretion of the-trial
THE HISTORICAL PROCESS SET OUT ABOVE, AS FIRST ESTABLISHED in
United States v. McMillan, is widely used today even though several
recent court decisions provide more relaxed rulings on
admissibility. For example, in United States v. Traficant*17* the court stated that:
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.
EXAMINATION REQUESTS AND REQUIRED EQUIPMENT
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.
Examples of such problems are:
- Credibility questions relating to the tape recorder operator
- Chain-of-custody contradictions
- 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.
The Federal Bureau of Investigation, for example, has a protocol
of required information, including:
- The original tape
- The tape recorders and related components used to produce the recording
- Written records of any damage or maintenance done to the recorders, accessories
and other submitted equipment
- 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.
- A typed transcript of the entire recording or, if that is not available,
transcriptions of the portions in question. The items listed above are examples
of what is required by a forensic expert as she begins an examination of questioned
Extraneous voices: background voices which at times appear to be as near as the primary voices (these can, at times, even block the primary
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.
FALSIFICATION OF TAPES
A QUALIFIED FORENSIC EXPERT DETERMINES
AUTHENTICATION by performing a number of scientific tests which detect evidence
of tampering or falsification. The four basic types of tampering are these:
- Deletion: the elimination of words or sounds by
stopping the tape and over-recording unwanted areas
- Obscuration: the mixing in of sounds of amplitude
sufficient to mask waveform patterns which originally would show stops and
starts in inappropriate places
- Transformation: the rearranging of words to change
con- tent or context
- Synthesis: the adding of words or sounds by artificial means or impersonation.
ELECTROMECHANICAL INDICATIONS OF FALSIFICATION
THESE ARE SOMETIMES REFERRED TO AS "ANOMALIES" AND include the following:
- Gaps: segments in a recording which represent
unexplained changes in content or context (a gap can contain buzzing, humming
- Transients: short, abrupt sounds exemplified by
clicks, pops, etc. (transients may indicate tape splicing)
- Fades: gradual loss of volume (fades can cause
inaudibility and are considered gaps when the recording becomes fully
- Equipment sounds: inconsistencies of context caused by the recording equipment itself (common equipment sounds include hums, static, whistles, and varying pitches)
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
- 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
- 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,
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
[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
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.
6 Id. 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).
18 United States v. King, 587 E2d 956, 961 (9th Cir. 1978)