What is CVSA?
Computerized Voice Stress Analyzer (CVSA) is a lie detection software program that is designed to measure the changes in a subject’s voice patterns caused by physical efforts or stress as he tries to hide deceptive responses when speaking during an investigative interview. The CVSA program is among lie detection technologies that purport to work by analyzing voice stresses (Damphousse, 2014). During testing process, a subject will be speaking as the microphone plugged into the computer taps his voice patterns for analysis. When the subject speaks, frequencies of his voice patterns will form dynamic graphs on the computer screen. They are these changes on the graph, because of frequencies of his voice patterns due to stress levels that will be correlated to truth or deception (Haddad et al., 2002). According to Hopkins et al. (2005), the voice stress analysis arose from the concept that for a subject under stress, microtremors in the vocal tract will always be transmitted in his speech. When a person is normal circumstances without stress, his muscles will be vibrating within the range of 8-12 Hz. However, the moment he develops stress his body will be preparing for fight or flight. This will be marked by increasing the readiness of his muscles to “spring into action”. In this regard, muscle vibrations will be increasing as a person forces himself to hide the truth/ deception (Hollien et al., 2008). In such case, as the proponents of the technology believe, the subject will be hiding deception. This is shown on the computer by the graph shape of his waveform tending to be flatter because of the prolonged stress of finding a favorable response to hide the truth (Hopkins et al., 2005).
Does the CVSA Technology Detect Deception Hiding/ Liars?
Various studies have revealed that the CVSA technology has shown unsatisfactory results regarding accuracy in detecting lies. Although the Polygraph Research has put its accuracy at 37% (The American Polygraph Association, 2002), the US National Institute of Justice study on detection accuracy and thus on sensitivity and specificity, has indicated the technology performing dismally at 15% (Damphousse, 2014). Forensic experts have noted that like polygraph, the CVSA does detect lies directly, but rather through variations in emotional stress (Hopkins et al., 2005). However, studies have shown that despite deception hiding, a number of factors may influence stress in an individual to make the waveform graph on the computer screen to flatten. Temporal physiological conditions such as increased blood pressure, sleeplessness, throat cancer, and illegal drug use are the first endogenous factors that can affect the results of the CVSA examinations (Hollien et al., 2008). Moreover, the relationship between the examiner and the subject will also determine the effectiveness of the device. If the examiners are not well trained, the results will be at large extent not accurate (Haddad et al., 2002). These factors will obviously cause variations in emotional and muscular stress in an individual. If an individual is influenced by the factors whether he is hiding deception or not, the CVSA will produce wrong results (Hollien et al., 2008).
The goal of the CVSA is just to convince a subject who is ignorant about how the program works that he cannot deceive the examiner because he will be detected (Hopkins et al., 2005). However, presently, there is increasing awareness about how it works, and people who are going to undergo its tests, are honing themselves with countermeasures to avoid the accurate results. The first tactic is the use of Machiavellian lie, whereby a person practices on advantageous abilities that will enable him to make deliberate lies during the CVSA interviews. It involves going and having enough rest, controlling breath, becoming nice to the examiner by smiling and developing rapport by being cooperative while testifying (Hollien et al., 2008). Thus, confidence and friendliness with the CVSA interviewer will help the subject to dodge accurate results (Haddad, et al., 2002). Apparently the level of accuracy for the CVSA technology to detect lies is very unsatisfactory (Haddad et al., 2002).
References
Damphousse, K.R. (2014).Voice Stress Analysis: Only 15 Percent of Lies about Drug Use
Detected in Field Test. Washington: NIJ. Retrieved on 15 December 2014 from http://www.nij.gov/journals/259/pages/voice-stress-analysis.aspx
Haddad, D. et al. (2002). Investigation and Evaluation of Voice Stress Analysis Technology.
New York: Office of Justice Programs, National Institute of Justice, Department of Justice.
Hopkins, C.S. et al. (2005).Evaluation of voice stress analysis technology. Proceedings of the
38th Hawaii International Conference on System Sciences.
Hollien et al. (2008). Evaluation of the NITV CVSA. Journal of Forensic Sciences, 53(1), pp.
183-193.
The American Polygraph Association. (2002). Detection of Deception: Truth vs. Myth.
Phoenix: APA National Office.
