Voice Stress Analysis (VSA/CVSA) vs Polygraph
Quick, convenient, and reliable, but can Voice Stress Analysis replace the polygraph test? Although voice stress analysis emerged over half a century after the polygraph’s invention, the technology has become one of the most widely touted lie detector alternatives.
The first voice stress analysis (VSA) device emerged in 1971. Called the Psychological Stress Evaluator (PSE), the original VSA equipment was developed by Dektor Counterintelligence and Security, Inc. to analyze inaudible microtremors indicative of deception. In 1988, NITV Federal Services invented the first Computer Voice Stress Analyzer (CVSA).
Right off the bat, we should reiterate that voice stress analysis doesn’t stack up to polygraphs. But that hasn’t stopped many CVSA proponents from comparing the two techniques.
VSA vs POLYGRAPH
- Technology Used
VSA relies on voice stress analysis, a technology that measures fluctuations in vocal micro-tremors. The absence of peer-reviewed validation makes this technology highly unreliable.
Meanwhile, polygraphs measure physiological arousal associated with deception. The technique primarily targets changes in involuntary functions controlled by the autonomic nervous system (ANS), such as heart rate, blood pressure, skin conductivity, and respiration.
Polygraphs analyze more factors, making the technique more credible than CVSA.
- Accuracy and Reliability
CVSA has an average accuracy rate of 50%, according to independent research.
According to the APA, tests conducted by qualified examiners can achieve impressive accuracy scores of 95%.
- Validity
Both CVSA and polygraphs are yet to achieve mainstream recognition within their respective scientific communities.
However, polygraph tests enjoy comparatively more approval due to their higher reliability.
- Transparency and Methodology
Polygraphs follow a more extensive testing methodology, which includes pre-test, in-test, and post-test phases, all implemented in the same session.
This comprehensive approach to lie detection enables examiners to collect more information, including admissions of guilt. It’s part of the reason the technique is more reliable.
- Applications
CVSA is almost exclusively limited to security and law enforcement agencies.
In contrast, polygraphs enjoy wider applications. You can find the technique in criminal detective work, government contracting, relationship counseling, and sports screening.
Other polygraph applications include relationship counseling, immigration screening, and sex offender monitoring.
COMMON MYTHS ASSOCIATED WITH VSA
Computer voice stress analysis is aggressively marketed as more reliable than polygraph tests, despite studies indicating otherwise. Here are some prevalent CVSA myths;
Lie Detection Purely Based on Voice – To draw conclusive reports, examiners must analyze more factors than voice alone.
Vocal Stress Automatically Equals Deception – Mental stress isn’t conclusive proof of deception. In fact, reliable lie detection tools like polygraphs don’t screen for mental stress.
Lie Detection is Measurable Over the Phone – It’s nearly impossible to detect dishonesty through a phone interview. A more reliable lie detection tool requires direct examiner-examinee interactions.
WHAT IS VOICE STRESS ANALYSIS?
Voice stress analysis is a technology that measures deception by analyzing certain involuntary vocal changes. As noted, the technology first emerged in 1971 before going digital in 1988.
Computer voice stress analysis utilizes a microphone and a computer device to detect inadvertent changes in an examinee’s body, which aren’t always perceptible to the human ear. Commonly analyzed metrics include fluctuations in tone, pitch, and rhythm.
The polygraph test is exceptionally reliable as it measures physiological changes that are difficult to manipulate. In contrast, computer voice stress analysis relies heavily on the micro-tremor concept. CVSA borrows from the theory that all human muscles experience low-amplitude, inadvertent oscillations called tremors. According to advocates, psychological stress can alter the frequency of vocal micro-tremors. Voice stress analyzers would then pick up those fluctuations, providing valuable hints of deception.
Law enforcement officers use voice stress analysis to accelerate detective work. Besides, some security agencies rely on the technique to screen job applicants or prequalify contractors.
VSA proponents promote the concept as being non-invasive. Unlike polygraphs, this technique doesn’t involve pinning sensors to an examinee’s body. But as you shall find, CVSA’s non-invasiveness doesn’t make it any less comfortable. The supposed benefit is certainly not a major drawcard when you consider that polygraph testing boasts a higher accuracy score.
HOW VSA WORKS
Voice stress analyzers examine fluctuations in vocal micro-tremors, which may indicate deception.
First, an examinee steps into a dedicated room to answer a set of questions. A microphone records their replies as a computer screen displays their voice patterns in real time.
Examiners then assess the data for evidence of higher-frequency changes in micro-tremors.
CVSA manufacturer contends that lying can impact vocal frequency. The company borrows from previous studies, which have shown that the psychological stress caused by deception may alter certain vocal parameters. But while these assertions are somewhat factual, other factors entirely unrelated to dishonesty may change a subject’s micro-tremors.
Other promoted CVSA benefits include;
Ease of use, relying primarily on a microphone
Remote setup, as examiners don’t necessarily have to be in the same room
Quick, often lasting a few minutes
Inexpensive, as it requires minimal equipment
SHOULD VSA BE USED FOR TRUTH VERIFICATION?
Voice stress analysis cannot be used for truth verification because it lacks scientific validation. Examiners should consider more verified methods, such as the polygraph.
Relying on peer-reviewed evidence-based techniques is the surest way to conduct legally defensible lie detection tests.
Despite widespread claims of CVSA’s efficacy, mounting evidence suggests that this method pales in comparison to a well-conducted polygraph exam. If you must use VSA, it’s best to combine it with polygraph tests.
KEY LIMITATIONS OF VSA/CVSA
Despite manufacturer claims, voice stress analysis has glaring limitations.
Notably, VSA measures changes that aren’t unique to deception. Fluctuations in vocal micro-tremors may also be indicative of emotional stress.
Other limitations include;
Potential influence of fear, anxiety, underlying medical illness, and the testing environment
Single-channel measurement, relying exclusively on vocal changes
High risks of misleading interpretations due to the smaller number of effectors analyzed
In light of these limitations, many agencies have since moved away from VSA to more reliable techniques like the polygraph.
WHY VSA REMAINS CONTROVERSIAL
Voice stress analysis has always been treated with skepticism due to the absence of peer-reviewed validation.
Also, professionally conducted polygraph tests can detect deception more accurately than CVSA. In contrast, there are no officially recognized CVSA peer reviews besides manufacturer claims and user testimonials.
Other points of controversy include;
Minimal recognition within the global scientific community
Legal concerns due to widespread inadmissibility
Ethical concerns, such as the potential for coercion and privacy violations
Risks of abuse and overreliance
WRAP UP
Computer voice stress analyzer is widely touted as a reliable lie detection technique. However, it’s not without limitations.
A lack of peer-review validation is the CVSA’s biggest drawback. Besides, the technique has a deplorably low accuracy score.
Not to mention the fact that it measures fewer effectors.
Polygraph offers a more reliable way to sniff out liars. The technique analyzes multiple physiological effectors and follows a comprehensive methodology, making it remarkably effective.
Click HERE to learn more about our validated polygraph testing options.
This page addresses the following issues:
- Voice Stress Analysis
- Computer Voice Stress Analysis
- VSA
- CVSA
- Accuracy of VSA
- Accuracy of CVSA
- Accuracy of Voice Stress Analysis
- How Accurate if Voice Stress Analysis
- Voice Stress vs Polygraph
- VSA vs Polygraph
- CVSA vs Polygraph
- Is VSA better than Polygraph?
- Is Voice Stress Analysis better than Polygraph?
- Is Polygraph better than VSA?
- Is Polygraph better than Voice Stress Analysis?