For decades, the California Department of Corrections and Rehabilitation used a pseudoscientific technology to assess prisoners’ credibility during investigations, even after researchers debunked the CVSA and after its manufacturer, NITV Federal Services, admitted that it was not capable of detecting lies, a Chronicle investigation has found.
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NITV Federal Services offers dozens of courses to law enforcement agencies each year and has sold its machines and training sessions to thousands of departments, billing the CVSA as a cheaper alternative to the polygraph test — another controversial lie-detector technology. Collectively, these California agencies have spent at least hundreds of thousands of taxpayer dollars on the CVSA since 2020, the Chronicle found.
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The CVSA purportedly works by measuring inaudible changes to a person’s speech patterns. According to an early 2000s training manual obtained by the Chronicle, a person’s vocal cords are “subject to physiological tremors” that diminish when they are stressed. Thus, a stressed person’s speech patterns would have a different frequency, and a different shape when plotted on a graph, than an unstressed person.
California’s prison system has moved to ban the use of a controversial lie-detector test — compared by one expert to a Ouija board or an astrological chart — following a Chronicle investigation into the technology and its impact on the incarcerated.
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While California’s prisons will no longer use the CVSA, the Chronicle’s investigation identified 13 other law enforcement agencies around the state that were still using the technology to interview prospective officers during the hiring process. At least three of these agencies had also recently used the tool during criminal investigations.
From the CVSA Wikipedia entry:
A 2013 paper published in Proceedings of Meetings on Acoustics reviewed the "scientific implausibility" of its principles and "ungrounded claims of the aggressive propaganda from sellers of voice stress analysis gadgets"