New Study Validates Accuracy of Computer Voice Stress Analyzer

Study Adds to Legacy of Professor James L. Chapman


Lewes, DE -- (SBWIRE) -- 01/11/2013 -- A newly published research study in the 2012 annual edition of the scientific journal Criminalistics and Court Expertise reports the accuracy rate of the Computer Voice Stress Analyzer (CVSA®) is greater than 95%, an assertion long made by the system’s manufacturer. The study’s results are further bolstered by current US Government funded voice analysis research which has established voice technologies performed well for border security applications.

The CVSA has been available to law enforcement agencies in the US since 1988, first as an analog device, and since 1997 in a digital version. The CVSA is the only Voice Stress Analyzer in the world with two US Patents and the only system worldwide incorporating the FACT® scoring system, which uses scientifically validated processes to reliably and precisely evaluate the results of CVSA examinations. The CVSA is now used by close to 2,000 agencies and is the most widely used truth verification system in the US.

The 18-year field study was conducted by the recently deceased Professor James L. Chapman. The study, titled “Long-Term Field Evaluation of Voice Stress Analysis In a North American Criminal Justice Setting” is the crowning achievement of Professor Chapman’s legacy. Professor Chapman was known as the world’s foremost authority on the application of Voice Stress Analysis technologies, and at the time of his passing he also served as the Director of Standards and Training for the National Association of Computer Voice Stress Analysts (NACVSA), the world’s largest professional association of Voice Stress Analysis practitioners. His career spanned over 40 years as a criminologist, educator and researcher, during which he conducted more than 15,000 Voice Stress Analysis examinations. The study’s co-author, Marigo Stathis, a neuroscientist and research analyst, has been the primary or co-author of 27 published scientific articles and studies focusing on various topics related to the human brain and biology.

Professor Chapman used the CVSA to conduct the research and the results achieved were highly consistent throughout the period the study’s data were collected. The study’s findings revealed the CVSA, when used as an investigative support tool, can accurately predict whether a person under investigation is being truthful or deceptive. The study’s findings are supported by scientifically-accepted statistical models, and by the 96.4% validated confession rate Professor Chapman attained during the course of the 18-year study. According to current scientific research and meta-analyses, police confession rates worldwide vary between 20-45%, with even the most experienced police interviewers only achieving a 50-55% confession rate. The CVSA was used as an investigative support tool by Professor Chapman to significantly increase confession rates above the 95% level. Empirical data collected by the CVSA’s manufacturer, US law enforcement and US military CVSA users have long supported such findings; however, this is the first independent and peer reviewed scientific study to validate these data. Additional studies and research are planned for the future.

During its upcoming annual convention in January 2013, the NACVSA will present the first annual Professor James L. Chapman “Award for Excellence.” The award will be presented to the individual who made the most significant contributions to the Voice Stress Analysis profession during 2012.

For further information please contact Carol Graham, Administrator for the NACVSA at