The computerized voice stress analyzer is a method of lie-detecting used by a growing number of police departments around the nation, despite the lack of substantive research proving its effectiveness. But though many experts have questioned its reliability, University Police have been using it during the hiring process and in criminal investigations for the past three years.
The voice stress analyzer detects inaudible changes in a person’s voice to identify whether they are lying. Though it is possible that a person’s voice changes when they lie, there is no substantive proof the machine can effectively monitor whether a person is telling the truth, two experts said.
“They’re saying you have frequency modulations, and when the frequency modulation changes that’s indicative of stress,” said Thomas Mauriello, a former University Police investigator who has worked with both the new voice analyzer and the long-standing polygraph lie detector. “All I’m saying is where do they get the basis for that?”
Dan Seiler, the former president and current secretary of the Maryland Polygraph Association, shares Mauriello’s reservations about the voice-stress analyzer.
“The research done by the Department of Defense Polygraph Institute shows no more than 50 percent [validity] for the voice stress analyzer,” he said. “Now, the polygraph’s reliability is up to 95 percent.”
Seiler, who has worked with versions of the voice analyzer and has more than 24 years of experience using polygraphs, said the voice analyzer system is used mostly for its psychological effect on a subject.
“The police use it more as a tool for interrogation. If I just gave you a lie detector test and you fail, you’re under a lot of pressure to tell the truth, especially if you think the machine is [credible],” he said. “If the voice stress analyzer was better, I’d use it, but … right now the polygraph is top dog.”
University Police spokeswoman Maj. Cathy Atwell supported her department’s occasional use of the voice stress analyzer, saying the department uses it because of its psychological effect on the person interviewed, not its ability to detect lies.
“I don’t see any evidence that it’s inefficient or useless,” Atwell said. “The value is more in what you get from the person being interviewed. The hope is that they will be more forthcoming [with the analyzer present].”
Potential recruits are all subject to the voice stress tests to gauge their honesty and determine the validity of their answers to important job interview questions, such as questions about criminal backgrounds.
“What we’re looking for is essentially the integrity of the applicants,” Atwell explained. “We don’t use [the analyzer] very often, and when we do use it in a criminal investigation, it’s voluntary.”
Mauriello agreed the psychological effects of the analyzer can be quite beneficial to an investigation.
“A lot of people become honest with you before you even turn the instrument on,” Mauriello said. But he still said the polygraph “far surpasses the voice stress analyzer.”
“Do I think that the voice-stress analyzer is an effective and valid instrument to detect deception? I would say absolutely not,” he said.
Mauriello said he thinks the polygraph is a much more effective and credible means of delving into the human psyche.
“The polygraph has a long history of credible use in the law enforcement community,” Mauriello said. “As a forensic scientist … I have not found any valid research or documentation to convince me that the voice stress analyzer is credible.”
The polygraph machine measures changes in the sympathetic nervous system, the part of the nervous system that activates in times of stress or crisis. It also monitors a subject’s pulse for heightened heart rates and skin perspiration, both common indicators someone is nervous and possibly lying, Mauriello said.
The price difference and training times are other important factors taken into account by police departments deciding on new truth detection technology. Whereas the voice analyzer costs anywhere from $9,995 to $12,995 to install in computers, a decent polygraph can be purchased for $5,950, according to the American Polygraph Association.
Departments also consider training differences between the two instruments. Polygraph users must obtain a license to use the technology and undergo a training process of up to five months and amounting to about $5,000. Voice stress users can be trained in three to six days and are more easily certified by other users.
Contact reporter Jeremy Arias at ariasdbk@gmail.com.
