Louise Dickson reports on the first use of Computerized Voice Stress Analysis (CVSA) by Canadian police in this puff piece published in the Victoria Times Colonist. Excerpt:
“Did you actually see Ruth shoot Billy?”
“Yes,” the suspect replied.
“Did you shoot Billy?”
But the image on the computer screen told another story. In this Florida case, a picture was worth 25 years.
The Florida investigator was using a computerized voice stress analyser to detect deception. Saanich police have the first analyser in use in Canada.
“It’s a very accurate instrument,” said Saanich police Sgt. Don Wiebe as he played the taped interrogation in the Florida case. “If done accurately and correctly by the operator, it will be 100 per cent effective in verifying truth.”
The Florida investigator, trying to get to the bottom of a a drug shooting, hooked up his suspect to the voice stress analyser. After a series of direct questions, it became apparent that both Ruth and her boyfriend had shot Billy.
Wiebe said that using the $16,000 analyser is as easy as hooking a microphone to a lapel. The microphone directs the sound into the software of the computer. The tool, used by 1,103 law enforcement agencies in the U.S., is portable and less intrusive than a polygraph test.
The machine works by measuring the FM frequency in the voice, Wiebe explained.
“Voices line up in two modulations, AM and FM. When you are speaking, your AM frequency rides on top of your FM frequency. If you are under considerable stress, the FM in your voice diminishes,” said Wiebe.
When someone gives a perfectly truthful answer, the voice stress analyser projects an image on the computer screen of a pyramid with diagonal lines. When someone lies, the diagonal lines diminish and plateau. The pyramid shape becomes more of a block.
Like polygraphy, CVSA, peddled by the “National Institute of Truth Verification,” is a pseudoscientific fraud. In the early 20th century, uncritical journalism of the kind we see here helped to delude the general public into believing in the myth of the polygraph. Now, in the early 21st century, the same process continues with respect to CVSA.