Law enforcement and corrections officers have long used the polygraph as a tool to confront a suspect or prisoner in an investigation. The polygraph is inadmissible in courts, but is widely used to exonerate innocent subjects and elicit confessions from others.
A new voice-analyzing tool -- Layered Voice Analysis (LVA) -- is gaining popularity among law enforcement and corrections agencies.
According to a segment on ABC's Primetime on March 31, 2006, at least 1,500 police or corrections agencies are using some type of voice-stress-analysis software when questioning subjects.
The broadcast prompted the reaction of critics who say the technology doesn't work.
The Wisconsin Department of Corrections (DOC) used LVA approximately 125 times in the last two years, according to Dan Westfield, security chief at the DOC. The software is used when questioning inmates during prison investigations. Westfield said LVA is not used to determine guilt or innocence, but rather to steer an investigation in the right direction.
The software measures frequencies in speech by running algorithms and recognizing, with a mathematical formula, patterns indicative of confusion and cognitive dissonance within speech, according to Dave Watson, chief operating officer of V, LLC, which markets LVA.
The software is typically loaded onto a laptop. During the interrogation, the subject talks into a microphone and the words are translated onscreen into graphs that measure the level of confusion or cognitive dissonance in the suspect's voice.
Pop-up boxes alert the interviewer of the deception level detected in the subject's voice with comments, such as: unsure, inaccuracy, probably false or false statement.
"It analyzes the voice and alerts the interviewer that there's something here," Westfield said. "Let's start questioning a little deeper on what we're talking about right now. It helps the interviewer get to the heart of something a little bit quicker."
The DOC doesn't use the polygraph because bringing in a polygraph expert from outside the prison is inconvenient, he said.
"To have our own people trained in use of this technology is more cost effective," Westfield said. "We can investigate and get it resolved quicker, because we have the people with expertise. When you take somebody from outside the DOC, you have to brief them on what's going on. They're not familiar with the environment. It's not like having somebody who works in the prisons; understands the prisons; understands the inmates and what's going on."
Five officers in the DOC are trained to use the LVA software, and were trained for three weeks by V, LLC at a cost of $2,000 each. The software itself costs about $10,000.
The DOC uses the tool to investigate inmate security issues, including suspicion of possession of intoxicants and threats against other inmates and guards, according to Westfield.
"The technology has also been used to clear misconduct where inmates have alleged that another [inmate] did this or that," Westfield said. "So it helped us confirm the fact that an inmate may or may not have done something. It's worked both ways."
In one case, an inmate said he saw another inmate with a shank -- a homemade prison weapon. The test administrator said, based on the results, he believed the accused inmate had in fact possessed an illegal weapon. The inmate later confessed to having the shank and flushing it down the toilet.
As with any tool, LVA is only as good as its operator, proponents say. Formulating questions and good follow-up questions is critical.
"It's like any other tool," Westfield said. "If you don't know how to use the tool, if you don't have some expertise in investigations, LVA is going to do nothing for you."
Truth or Deception?
Critics, however, say this technology doesn't