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Test of the Computer Voice Stress Analyzer (CVSA) Theory of Operation

NCJ Number
Polygraph Volume: 31 Issue: 2 Dated: 2002 Pages: 72-86
Victor L. Cestaro
Deedra Senter
Date Published
15 pages
This study evaluated the theory of operation of a second-generation voice analyzer, the Computer Voice Stress Analyzer (CVSA).
The Computer Voice Stress Analyzer (CVAS), manufactured by the National Institute of Truth Verification, is an instrument used to detect deception in voice responses. It analyzes and displays responses in real time, using state of the art computer technology. The theory behind the CVAS is that it detects physiological microtremor associated with muscles in the voice mechanism. This study was designed to test the underlying electronic theory of operation of the CVSA. The CVSA input/output was evaluated using simulation signals from laboratory test generators. The results of the laboratory test show that the CVSA functioned electrically according to frequency modulation detection theory. If there is an inverse relationship between stress and voice microtremor amplitude and the changes have a sufficient signal value to be detected by the CVSA, than it is possible to see pattern changes in the CVSA output under different levels of stress. The CVSA instrument was shown to detect discrete changes in speech fundamental frequency using laboratory instruments to simulate voice microtremor, confirming the underlying theory of operation. Figures and references