A measure of truth: New technology analyzes voice patterns to try to root out lies

Nevada, Mo. -- The Nevada Police Department has a new tool to help investigators get to the truth of the matter, but it isn't a new piece of equipment, it's computer software. Comput-er Voice Stress Analysis analyzes a person's voice and can detect changes that are imperceptible to the unaided human ear.

"There's not much to look at," Captain Jimmy Dye said. "It's a software program that loads up on a laptop. Other than that all you really have is a microphone hooked to a computer. It's not like a polygraph."

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A polygraph (often misleadingly referred to as a lie detector) is physically connected to the person being questioned and records various physical indicators such as respiration, pulse and blood pressure. VSA is not connected to a person at all but the microphone input is used to analyze the voice.

"VSA, all it does is detect minute changes in your voice when lying," Dye said. "You set up a baseline by asking questions you already know the answers to, then start asking questions you don't know the answer to."

The department has two officers trained in the use of the software and Detective Jens Barclay explained how the software detected those changes.

"It's based on AM and FM frequencies," Barclay said. "The AM part carries the FM signal and the FM goes away when someone is being dishonest."

The department has had the software since January, but Barclay just received his training on it this month.

"I just finished the training and I've only actually run one real test with it," Barclay said.

One reason that Barclay hasn't used it more is that people on the other side of an investigation often don't want police to verify the truth of their statements.

"Surprisingly, most people you ask don't want to take it if they have something to hide," Barclay said humorously. "People will often ask for it to be used when they want to prove their innocence but usually when we ask someone it's because we have a pretty good idea it's them. When we tell them we'd like them to voluntarily take the test they say no. Of course, saying no tells us something, too."

Before the department had the software they had to take someone to Springfield and have the Missouri Highway Patrol use a polygraph. It took a lot of time and was inconvenient. A laptop can be carried with a detective wherever they are and is fairly unobtrusive. However, that is a fairly recent development of the technology.

"It's only been in the last seven years that it's been in a laptop configuration," Barclay said. "CVSA was developed in the '80s by the military and adapted by an individual for civilian use. It's not a 100 percent thing, you can't use it in court. The courts haven't taken judicial notice of it or recognized it as a validated scientific principle."