LIE DETECTION THROUGH VOICE ANALYSIS

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• Collection: STARGATE
• Document Number (FOIA) /ESDN (CREST): CIA-RDP96-00788R002000150003-2
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• Document Creation Date: November 4, 2016
• Document Release Date: June 22, 1998
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• Content Type: PAPER

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LIE DETECTION THROUGH VOICE ANALYSIS
By
Frederick C. Link*
"Have you read the articles on voice analysis in recent PlayboyI
and Penthouse2 magazines?"
"Have you seen the movie 'The Trial of Billy Jack?'"
"Or, have you watched television presentations on 'What voice
analysis shows really happened in the Kennedy assassination."'
If the answer to any one of these is "yes," you may well have been left
with the impression that voice'analysis is the cure-all for detection-of-
deception problems in law enforcement.
Lie detection through voice analysis has been glamorized by publicity in
the popular media, and all this glitter has led many citizens to form an un-
realistically high opinion of the present value of voice analysis. However,
television, movies and popular magazines have not given unbiased, impartial
~aresentations of the facts regarding the effectiveness of voice analysis for
J ie detection.
r
At the
p
esent time, no military law enforcement agency is using voice
analysis for lie detection, although all of these agencies use the polygraph
technique when it is appropriate. There are good reasons for this nonuse
of voice analysis. While voice analysis may some day in the future be devel-
c,ped to the point where it is useful for military lie detection, that day has
rot yet arrived. In order to understand why this is so, let us look at some
pertinent facts.
The Basis of Voice Analysis
Although human speech is the result of a very complicated process, several
different aspects of the voice can be analyzed. The manufacturer of one voice
E:ialysis device (the Psychological stress Evaluator) relates that the single, Lf
integrated sound that we hear as human speech is composed of at least three
different sounds blended together: the basic sound, formant sound, and the
microtremor.
The basic sound is formed by air being forced over the vocal cords and
is a signal generally between 100 and 300 hertz, (1 hertz, a frequency equal
too one cycle a second). This frequency forms the base of the combined signals
t.1at constitute the voice.
The author is a Chief Warrant Officer, Corps of Military Police, U.S.
Army,. and an instructor in polygraph technique in the Army Polygraph School
au Fort McClellan, Ala. The article is reprinted from the Military Police
L3 .a Enforcement Journal, Spring, 1976, with permission of the jornal and the
i.i thor.
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The formant sounds are resonances (vibrations) created by the various
cavities of the head, especially the mouth, which add a second amplitude-
modulated sound to the voice.
Finally, the microtremor (an inaudible frequency modulation) is super_
imposed on the base and formant sounds. 19
The microtremor signal is normally in the range of 8 to 12 hertz andjit
is present in all normal speech. However, when a speaker begins to feel'in-
ternal stress an d those speech processes that are normally mediated by t1
autonomic nervous system are brought under conscious control, then the micro-
tremors are suppressed and disappear from the voice. When this presence or
absence of the microtremor is recorded and charted with suitable equipment,
it is possible to determine from speech whether a speaker shows stress. Under
suitable testing conditions, the presence of stress would be an indication of
lying, and the absence of stress would show truthfulness.3
Another voice analysis device, the Mark II Voice Analyzer, is claimed
to function by extracting and processing the tremolo effect from the voice, a
process reeated to but not the same as that used in the Psychological Stress
Evaluator.
Voice analysis devices have been highly marketable and they have been
popping up like mushrooms. Although these devices differ from each other in
their exact modes of operation and in their finished designs, they are all
essentially similar in that they extract and process some signal contained in
speech. The devices offered by the manufacturers range in price from about
$3,500.00 up. Usually., these systems consist basically of a tape recorder;
the analyzer itself, which gives a chart readout and, in at least one case,
a numerical readout and the accessories such as microphones, telephone tEDs,
and the like.
Does Voice Analysis Really Work in Lie Detection?
The manufacturers of these devices, of course, claim that they really
work. In fact, they claim them to be better than the polygraph in accuracy,
reliability, ease of use, comfort and dignity of the examinee, and in just
about any other respect you can imagine. Additionally, the manufacturers of
some of the devices have gotten nation-wide publicity by claiming to have
analyzed and determined the truthfulness of the recorded statements of such
contemporary figures as Lee Harvey Oswald, Edward Kennedy, and Patty Hearst.
They further claim to have determined the truthfulness of the statements
made by these persons. We will deal with these latter claims further on in
this paper.
Military attitudes on voice analysis for lie detection are based on teE-s
of some of these devices made by several military agencies and on validation.
research conducted by a civilian institution under contract to the Army.
The Air Force tested a Psychological Stress Evaluator for lie detection and
found it "not useful."t6 The National Security Agency tested a Psychologica=
Stress Evaluator and found it "insufficiently reliable."7 The Army obtained
three Psychological Stress Evaluators and used them in a study of lie detection
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conducted by Dr. Joseph Kubis of Fordham University. Following this study,
the Army dismantled two of the devices and transferred the third one to th
Air Force for research in areas not related to the detection of deception.
'' The Kubis study,9 completed in 1973, provides the primary justification
for the Army's nonuse of voice analysis. It is also a very interesting and
enlightening document on the relative effectiveness of the polygraph tech-
nique, voice-stress analysis, and investigator intuition. In essence, Dr.
Kubis put a number of volunteers through a crime situation in which money way
stolen from a purse. The volunteers were placed in groups of three in whi.ch~
one person stole the money, the second acted as a lookout, and the third
person had no connection with the crime whatsoever. After the crime had been
comranitted, all three persons were tested to attempt to determine what their
individual roles in the crime had been. In the structure of a polygraph ex-
amination situation, the suspects were given a polygraph examination while at
the same time their answers were tape-recorded. These tape recordings were
subsequently analyzed with two different voice analysis devices to attempt to
determine each suspect's role. Finally, the examination was watched by ob-
servers who attempted to tell if the suspects were lying or telling the truth
just by looking at them and interpreting their actions.
Kubis' study concluded that the polygraph technique had high validity,
observation of behavior was second most effective in determining who did what,
and voice analysis came off a poor third in detecting deception in this ex-
periment. In the words of Dr. Kubis: "Essentially, the findings indicated
the clear inferiority of voice analysis in its present state of development,
not only to the polygraph but also to judgments made on the basis of simply
observing subjects' behavior."1-0 He further says: "The results failed to
demonstrate that either of the voice-analysis techniques was effective in
identifying the three basic roles of thief, lookout, and innocent suspect in
the simulated theft. In contrast, the polygraph achieved an accuracy score
of 76 percent, a value comparable'to that obtained in previous studies using
the simulated theft paradigm."11 This validation effort provided the militaiy
community with a scientifically researched basis for rejecting voice analysis
as a lie detection technique at this time.
Dr. Kubis does not conclude that voice analysis for lie detection is
unworkable, only that presently available voice analysis equipment does not
fill the bill. He attributes the failure of voice analysis in his experiment
to "a matter of insensitivity or other inadequacy in the devices themselves
in their present state of development."12 Perhaps someday in the future,
voice analysis will be developed to the point where it is usable for lie de-
tection.
It should be noted that the manufacturers of the equipment and some of
its users have criticized the Kubis study on technical grounds. These criti-
cisms range from the claim that the tape recordings were of such poor quality
they could not be analyzed to the claim that the requirements of the research
contract were not met. Therefore, it is claimed that the results and con-
clusions of the Kubis study are invalid.13 This appears to be a somewhat
extreme position and there is probably little valid reason to doubt the over-
all conclusions of the study. Nevertheless, a new validation study is being
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conducted by a group at the Michigan State University, but so far no findings
have been announced.
Can Voice Analysis Determine If Public Figures Are Telling
The Truth in Public Statements?
Probably the most effective publicity for voice analysis has come from
the media that ran sensational stories about the analysis of public statements
made by newsworthy persons. The publicity centered primarily about the quest-ions
of whether Lee Harvey Oswald shot President Kennedy, whether Oswald acted alJne,
and whether there was a conspiracy among various unnamed persons acting to shoot
Kennedy. The leading article on this subject was written by a trained voice
analyst. The article, entitled "Lee Harvey Oswald Was Innocent,"14 appeared
in the April 1975 issue of "Penthouse" magazine. It contained a quite de-
tailed account of how the author had determined Oswald's innocence, and many
other details of the Kennedy assassination, through voice analysis. Naturally,
as indicated by the title of the article, the most significant conclusion war-
that Oswald was most probably telling the truth when he denied shooting Presi-
dent Kennedy.
More recently, another prominent voice analyst was reported in the press15
to have analyzed the tapes made by Patty Hearst while she was under the domina-
tion of the Symbionese Liberation Army (SLA). This recognized authority on
voice analysis concluded that Patty Hearst made all of her antisocial state-
ments under duress. He said she was not telling the truth when she claimed
to have voluntarily joined the SLA and to have voluntarily participated in
the bank robberies and other illegal activities perpetrated by the SLA. He
said she was innocent of any voluntary wrongdoing, and was doing only what she
was forced to do. All of these conclusions were formed on the basis of this
authority's analysis of the Hearst tapes.
On June 4 and 5, 1974, a subcommittee of the Committee on Government
Operations of the House of Representatives of the United States held hearing
on "The Use of Polygraphs and similar Devices by Federal Agencies." Various
advocates of the voice analysis lie detection technique testified before this
subcommittee. A position paper prepared by one manufacturer of voice analysis
devices said:
Because the PSE uses the voice as a medium for stress measure-
ment, the question' has been raised concerning the ability to
detect attempted deception of truthfulness from television or
radio broadcasts. It is indeed a fact that the PSE can be used
to determine the stress levels on the part of the speaker under
these circumstances. However, as has been discussed previously,
lie detection is an interpretative or analytical process which
requires certain control elements to allow equating the stress
indications to attempted deception, as opposed to any other
stress cause. Without these controls, appropriate pre test,
properly structured examination, and post-test interview in-
dications of stress remain just that. (sic) It would be in-
teresting, indeed, if lie detection could be accomplished un-
der such circumstances, but it cannot.t116
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The devr.Zr j~~,r of anoLhcr of the voice analyzers told the subcommittee:
"While th': Mark II can provide data on the stress occurring
in dialog, our experience to date shows that this is an
exceedingly complex area. Patterns of stress reactions occur
but, at present, we cannot be certain as to their meanings.
Therefore, we do not believe that the Mark II or any other
instrument currently available can analyze routine dialogs
and determine deception based upon our present knowledge.,,17
He also stated that:
In an early paper on voice analysis validation, two researchers concluded:
... For example, it has been s
to tape record a presidential newssconfere' nceofromet egtele-
vision coverage and determine-if the president was lying. It
would of course be possible to analyze the president's speech
and one would also be able to detect the presence of psycho-
logical stress in it. But unless he volunteered to answer the
questions from a structured interview, it would be impossible
to determine if psychological stress derived from lying or other
sources. Was the stress caused by a lie, an angry gesture from
the crowd, an extraneous thought, or a gas pain? All could
produce psychological stress."119
At these same hearings, the president of the voice
analysis
society, who is also a medical doctor, made this statement: professional
"Another charge that is made is that the Psychologic Stress Evaluator
(PSE-1 or PSE-101) can and may be used in a clandestine fashion. It is true
that tape recordings may be run in a clandestine fashion, in a face-to-face
conversation, off the telephone, and off the television.
formal testing situations and structure the on1 However, without
achieve from these tests is that the individual y evaluation that you can
or they are not stressing. are talking to is stressing
g. From this type of recording no type of truth
evaluation could be undertaken. If a person is speaking with great emotion
or conviction, the recording will show stress, as it should, mirroring that
emotion or conviction.""20
Finally, the voice analyst who has now declared Patty Hearst to be innocent
of all the offenses of which she is suspected reported to this Congressional
subcommittee:
"The system, the PSE as a lie detector cannot be used without
the knowledge of the individual because detection requires a
very specific set of circumstances, which means a personal
167
"?.. We just don't know enough to be able to truthfully say
what the patterns of tension in dialog mean. And I am afraid
anyone can find support for whatever interpretation he wishes
to make from these patterns
Thi
.
s is very bad obviously.iYlg
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confrontation, the pretesting of you, the very rigid test of
a section of test questions which must be reviewed prior to the
test. . . . You cannot conduct detection (of deception) tests
surreptitiously. It is impossible with our equipment, to the
best of our knowledge, or anyone else's equipment."21
These statements made to the Congress by the voice analysis group appear
to conflict with the claims that have found their way into print in the popular
press. In view of the inconsistent data coming from what are essentially the
same sources, it seems difficult to decide if voice analysis of public sta~o,e-
ments works or not.
This brief overview of voice analysis has indicated that, while voice
analysis appears to be scientifically based on involuntary psychophysiolog..cal
phenomena, hard evidence that the voice analysis lie-detection technique is
effective has not been introduced. It further seems that, at a minimum, much
further testing and refinement will be required before voice analysis can )e
considered useful for military lie detection. Resolution of these problems
does not seem to be enhanced by inconsistent statements made by the experts in
voice analysis. Until a scientifically acceptable validity rate for voice
analysis (that approaches the validity rate of the polygraph technique) is
established and, until the boundaries are clearly established for what voice
analysis can and cannot do, it does not seem reasonable that voice analysis
for lie-detection ought to be adopted by any of the military services.
1Craig Vetter, "The Lie Machine," Pla bo XX, 4 (April 1973), pp. 92-4,
102, 164, 166, 168, 170, 174.
2George O'Toole, "Lee Harvey Oswald Was Innocent," Penthouse, VI, 8
(April 1975), PP. 45-46, 124-127, 132.
3Hearings Before a Subcommittee of the Committee on Government Operations,
House of Representatives, Ninety-third Congress, 2d. Session, "The Use of Poly-
graphs and Similar Devices by Federal Agencies," Government Printing Office,
Washington, D.C., 1974, p. 238.
4Advertising material for the Mark II Voice Analyzer, Law Enforcement
Associates, Inc., 1975.
5Art Dworken, "Patty Hearst Not Guilty," National Enquirer, September 23,
1975, P. 5.
6Hearings, p. 429.
71bid., p. 429.
8Ibi.d., p. 428?
9Joseph F. Kubis, "Comparison of Voice Analysis and Polygraph as Lie
Detection Procedures," Final Report Contract DkkD05-72_C 0217r U.S. Army
Footnotes:
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Land Warfare Laboratory, Aberdeen Proving Ground, Maryland, August, 1973.
10Ibid., p. 31.
11 Ibid., p. iii.
.12 Ibid., p. iii.
13 Hearings, pp. 301-310.
140'Toole.
15Dworken.
16 Hearings,
17Hearings,
18 Hearings,
19Hearings,
20Hearings,
21Hearings,
p. 236.
P. 395.
p. 400.
pp. 292, 293.
P. 332.
P. 350.
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