There are a number of differences between a lie detector test and a voice stress test. Before we dive into that, it is important to note that the polygraph and voice stress tests are both considered lie detector tests.
When voice stress test (VSA) technology was first sold in 1970, there was a stampede to purchase VSA and use it in both the private sector and law enforcement. Huge numbers of polygraph examiners were dropping the outdated and primitive polygraph for the modern voice stress test. Because of the many polygraph defections to VSA, the polygraph business, which is controlled by the American Polygraph association (APA) began to lobby states to pass laws with a very secret clause. The clause defined a “lie detector” as only a polygraph machine, thus forbidding any other type of lie detection system, mainly VSA. At one time, about 18 states had those polygraph only laws. Over the years, almost all of those states repealed those polygraph only laws. Much rich content material on this matter is offered at computer voice stress analysis accuracy.
Instead of demanding accuracy of their polygraph machines, training techniques, ethics and morals from their polygraph examiners and their polygraph schools, the APA organization and its members chose to waste time using lies to try to eliminate the only truth verification system that had been proven superior to the polygraph system in terms of reliability, effectiveness and validity. That system was and still is voice stress analysis test. It was a former U.S. Colonel of Counter-Intelligence and a US government trained polygraph examiner who co-invented the voice stress test in 1970. It was another former U.S. Government trained polygraph examiner, with a Master’s Degree in Psychology, who wrote and published a book in 1981 that validated the complete VSA technology and techniques.
Many independent articles and studies have documented the very flawed polygraph technology and techniques. The National Academies of Science (NAS) is a worldwide organization of experts that began in 1863. In 2003, NAS published a very long and detailed book called The Polygraph and Lie Detection. The experts in NAS basically destroyed the credibility of the technology and training techniques that have been used by the polygraph business since polygraph began in about 1917. The NAS experts showed why the polygraph system should not be used for truth verification because of its lack of credibility.
The polygraph has been proven by studies for decades to be a very outdated form of truth verification. The polygraph business has never been able to agree on machine formats or training techniques. The polygraph device continues to be changed by adding more wires for foot pads, seat pads and finger clips to detect counter-measures. A drug dictionary was added to the polygraph to tell the examiner what functions will be affected by which drugs, legal and non-legal. Different training and testing techniques are constantly being invented. But, the APA seems to keep saying “This time the accuracy is better”. Among its many limitations and drawbacks, polygraph tests need to be done in a sterile room so the subject cannot use objects in the room to conduct a counter-measure to beat the test. The APA says a special chair should be used for the polygraph test.