CVSA and LHO

[Charles Collins]

Computer Voice Stress Analysis (CVSA) is a tool used by law enforcement, similar to how the polygraph is used. Here is an example:

Florida, Cocoa P.D.  – Analyst/Det. Gordon Chase was assigned to review the ‘cold’ homicide cases at his department While reviewing the first case which involved the brutal murder of a young woman six years prior, Det. Chase noticed that both suspects had voluntarily taken and passed polygraph examinations and because of that, were no longer considered suspects. He also discovered that both had given sworn, tape recorded statements in which they had denied any involvement in the murder. Det. Chase analyzed the taped statements utilizing the CVSA and while he was able to clear one suspect, the other suspect displayed deception when she denied committing the murder. Det. Chase located the second suspect and requested that she come in for questioning. When she appeared for questioning, the suspect agreed to take a CVSA exam. The CVSA exam clearly indicated that she was the one that had killed the young woman six years earlier. After forty minutes of interrogation, the suspect admitted to the murder and also how she had disposed of the murder weapon.

Sean R. DeGrilla has published an interesting new book titled “Malcontent - Lee Harvey Oswald’s Confession By Conduct.” In one section of the book CVSA is utilized on several recordings of LHO from 1963. And it demonstrated that LHO was being deceptive regarding the shootings.

An interesting book, definitely recommended!

[John Iacoletti]

Voice stress analysis is pseudoscientific nonsense.

[Charles Collins]

Voice stress analysis is pseudoscientific nonsense.

The CVSA is scientifically proven through lab and field testing to have a greater than 98% accuracy rating, making it the ideal truth verification tool for the pre-employment vetting process.

https://www.cvsa1.com/law-enforcement/using-the-cvsa-to-screen-police-recruits-during-the-pre-employment-interview-process/

[John Iacoletti]

Says the company trying to sell the equipment. Let’s see the peer-reviewed studies.

[Charles Collins]

Says the company trying to sell the equipment. Let’s see the peer-reviewed studies.

http://languagelog.ldc.upenn.edu/myl/ChapmanStathis2012.pdf

[John Iacoletti]

My reading of this study is that it tested the efficacy of using CVSA in obtaining confessions (much like “lie-detector” tests are used for), not in actually detecting deception.

[John Iacoletti]

https://www.ncjrs.gov/pdffiles1/nij/193832.pdf

“CONCLUSION
After reviewing the three technical tests performed, it could be stated that these two VSA units do recognize stress. Although these systems state they detect deception, this was not proven. This study does show, from a number of speech under stress studies, that linear and non-linear features are useful for stress classification. Due to the lack of deceptive stress data available, classification of deceptive stress versus emotional stress or physical stress was not tested. This is a vital role in the detection and classification of stress. Many suspects are under an extreme amount of stress when being interrogated. Do these VSA systems actually differentiate between the different types of stress? This still needs to be proven.“

[Charles Collins]

My reading of this study is that it tested the efficacy of using CVSA in obtaining confessions (much like “lie-detector” tests are used for), not in actually detecting deception.

As a key example, in the Grand Larceny case with 20 suspects, 19 of the examinations resulted in No Stress Indicated, and only one resulted in Stress Indicated – which in turn resulted in a confession. The Bernoulli Probability of having had 20 successful evaluations out of 20 examinations was less than 1 in 1,000,000. If VSA were simply a prop to obtain confessions, it would have been virtually impossible to achieve such specific and unerring results.


The deception is determined by the answers to carefully crafted questions which are designed for that purpose. (Hence, Barney Fife might have a little problem using the system.)