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Studies Validating Voice Stress Analysis |
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Air Force Research Laboratory,
Rome, NY, October, 2000. Funded by the National Institute of Justice, a
three-year study by the AFRL determined that voice stress analysis achieved
an accuracy rate of 100% when used to detect stress in 45 known-conclusion
responses. (Available from
http://extraafrl.af.mil/news/fa1100/features/detects:stress:feature.pdf) |
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2. |
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Cestaro, V.
Department of Defense Polygraph Institute, Ft. McClellan, AL. “A Comparison
Between Decision Accuracy Rates Obtained Using the Polygraph Instrument and
the Computer Voice Stress Analyzer in the Absence of Jeopardy”,
August, 1995. Cestaro reports that “the lab simulations established
that the CVSA performs electrically according to the manufacturer’s theory of
operation” and, even in the absence of jeopardy, which is a basic requirement
in detection of deception, “These data indicate that there may be a
systematic and predictable relationship between voice patterns and stress
related to deception” (Available from DoD web site:
www.dodpi.army.mil/research/research.htm) |
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Tippett, R. Florida
Department of Law Enforcement. “Comparative Analysis Study of the
Computer Voice Stress Analyzer and Polygraph”, August, 1994. Both a
polygraph and voice stress examiner, S/A Tippett examined 54 individuals that
were convicted sex offenders on probation and in treatment for their
crimes. His conclusions were: “With these 54 examinations, there was a
100% agreement between the CVSA and the polygraph. The number of
examinees that were found to be deceptive (DI) were 35 and the number of
examinees found to be not deceptive (NDI) were 19. As a result of this
study, it appears that the CVSA is as effective as polygraph, which is the
question this study set out to answer” (Available from University of
Missouri web site: www.umr.edu/~police/cvsa/cvsamenu/htm) |
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4. |
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Ruiz, Legros, & Guell,
1990. Voice analysis to predict the psychological or physical state of
a speaker. Published in Aviation, Space, and Environmental Medicine,
1990. Ruiz et al. reports that their “research suggests that
psychological stress may be detected as acoustic modifications in the
fundamental frequency of a speakers voice” and “that the fundamental
frequency of the vocal signal is slowly modulated (8-14 Hz) during speech in
an emotionally neutral situation. In situations demanding increased
‘mental or psychomotor’ activity, the 8-14 Hz modulation then decreases as
the striated muscles surrounding the vocal cords contract in response to the
arousal, thus limiting the natural trembling” (Available from Library of
Congress). |
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5. |
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Chapman, J. Criminal
Justice Department, Corning Community College, NY. “The Psychological
Stress Evaluator As A Tool For Eliciting Confessions”, 1989. Chapman
selected 211 criminal responses at random from 2,109 known-conclusion
responses where voice stress analysis was used to test suspects.
Professor Chapman’s study confirmed that voice stress analysis was accurate
when utilized as a truth verification device and produced a confession rate
of 94.8% of the responses where deception was indicated (Available from
NITV). |
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6. |
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Brockway, B.F., University
of Colorado School of Nursing, Denver, Colorado. “Situational Stress
and Temporal Changes In Self-Report and Vocal Measurements.” Presented
to the annual meeting of the American Association For the Advancement of
Science, February, 1977. Brockway’s study reports that voice stress
analysis does depict predictable and self-reported anxiety (Available from
Library of Congress). |
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7. |
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Smith, G.A. “Voice
Analysis For Measurement Of Anxiety.” British Journal of Medical
Psychology, 1977. The author concludes that voice stress analysis
is a valid measure of anxiety (Available from Library of Congress). |
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8. |
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Borgen, L.A., Goodman,
L.I., Parke-Davis Research Laboratories, Ann Arbor, MI. “Voice Stress
Analysis of Anxiolytic Drug Effects.” Results of the study indicated
that voice stress analysis of the verbal responses correlated well with the
other physiological responses to acute stress (Available from Library of
Congress). |
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9. |
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Inbar, G.F., Eden, G.
Dept. of Electrical Engineering Technion, Israel Institute of Technology,
Haifa, Israel. “Psychological Stress Evaluators: EMG Correlation With
Voice Tremor” published in Biology of Cybernetics, 1976. Inbar
and Eden were able to independently verify the existence of the 8-14 Hertz
‘micro-tremor’ and to trace its origins to the central nervous system
(Available from Library of Congress). |
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10. |
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Wiggins, S.L., McCranie,
M.L., and Bailey, P. Department of Psychiatry, Medical College of
Georgia, Augusta, Georgia. “Assessment of Voice Stress In Children”.
Published in the Journal of Nervous Mental Disorders, 1975. The
authors concluded that “audio stress can be detected with a voice stress
analyzer in psychiatric patients during the course of therapy and that the
VSA could serve as a useful tool for this purpose” (Available from Library of
Congress). |
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11. |
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Heisse, J. “Is The
Micro-Tremor Usable? - The Micro-Muscle Tremor In The Voice.” U.S.
House Subcommittee of the Committee on Government Operations, 1974.
Heisse analyzed 91 known-conclusion criminal responses utilizing voice stress
analysis and determined that “Audio stress analysis seems to be valid in
detecting changes in various psycho physiological parameters so that a
trained examiner utilizing standard techniques can evaluate these changes and
thus utilize the instrument in truth and deception” (Available from Library
of Congress). |
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12. |
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Brenner, M. “Stage
Fright and Steven’s Law.” Dept. of Psychology, Ohio State University,
presented at the convention of the Eastern Psychological Association,
April, 1974. Brenner, utilizing a voice stress analyzer, established
that the frequency of vocal stress increased as a function of audience size
(Available from Library of Congress). |
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13. |
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Lippold, O.
“Oscillations In The Stretch Reflex Arc And The Origin Of The Rhythmical 8-12
C/S Component Of The Physiological Tremor.” The Journal Of
Physiology, February, 1970. Lippold first discovers the
physiological tremor in the human voice in the 8-12 Hz range (Available from
Library of Congress). |
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14. |
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Lippold, O., Redfearn, J.,
Vuco, R. “The Rhythmical Activity Of Groups Of Muscle Units In The
Voluntary Contraction Of Muscle.” The Journal Of Physiology,
August, 1957. Lippold, Redfearn and Vuco begin exploring the
correlation between muscle activity and stress (Available from Library of
Congress). |