Greenacres to buy voice-stress analysis system, a technology some studies question
By Willie Howard
Palm Beach Post Staff Writer
Updated: 8:19 p.m. Wednesday, Dec. 28, 2011
Posted: 6:28 p.m. Wednesday, Dec. 28, 2011
GREENACRES — The city’s Department of Public Safety will buy a voice-stress analysis system for interrogating suspects and screening job applicants – even though some studies say the system that measures slight changes in the human voice can be unreliable in determining whether a person is telling the truth.
The city council recently approved spending $16,084 in forfeiture money on a Computer Voice Stress Analyzer II system for police interrogations, as well on as audio transmitters and receivers for use in police investigations.
Michael Porath, director of the city’s Department of Public Safety, said the department will begin using the voice-stress analysis system in the spring after employees have been trained on it.
The department also pays a company to administer polygraph tests as needed for interrogations.
"The CVSA is another tool that our agency will use to conduct investigations," Porath said. "it will allow the detectives to see if the person is being deceptive in the answers they’re giving."
Suspects in major cases have been taken from Greenacres to other departments for voice-stress tests in the past, Porath said.
According to the West Palm Beach-based National Institute for Truth Verification, the company that makes voice-stress analysis equipment, the system has an accuracy rate "exceeding 96 percent" and has a false-positive rate of 0.7 percent.
But a study published by the National Institute of Justice found that voice-stress technology was "no better than flipping a coin" in detecting lies about drug use. The study noted, however, that the presence of a voice-stress system during an interrogation made those being questioned less likely to lie.
The voice-stress system is used by 148 other Florida law-enforcement agencies, according to the manufacturer. They include the Palm Beach County Sheriff’s Office’s Special Investigations Division.
