Lies, damned lies and a new way to detect them

By Deborah Hill Cone

Friday 17th August 2001 1 Comment

A high-tech voice test might be just what People's Bank witch-hunt needs

TO TRACK THE TRUTH: Dan Thompson uses the CVSA system to check for voice micro-tremors that indicate deception

Employers concerned about staff theft now have the option of asking staff to take a voice lie-detector test - new technology said to have replaced the old-fashioned polygraph.

Auckland firm Auckland Investigations has imported the country's first computer voice stress analyser (CVSA), a high-tech system of analysing stress tremors in a person's voice to judge whether they are lying or not.

David Oughton, the investigator hired to hunt down People's Bank leaks, might also find the system useful.

How it works: the voice is made up of audible AM and inaudible FM sound waves. With the onset of stress, such as when someone is lying, the cyclic vibration changes or stops completely and causes the inaudible FM component to diminish or disappear. A change to the micro-tremors of the voice can be detected by the CVSA, which indicates the presence of stress or - depending on its application - deception.

Investigator Dan Thompson, one of only six private investigators authorised to use the system internationally, said the CVSA was more reliable than a polygraph.

"It all sounds a bit hocus pocus but if you start looking at the evidence ... you can see [why] this particular instrument outstripped the polygraph internationally."

The polygraph, which measures a range of physical reactions to stress such as heart rate and sweat production, is not used in New Zealand - although most people are familiar with them from seeing them on the movies and in US cases such as that of congressman Gary Condit.

The CVSA equipment cost about $30,000, about a third of the cost of a polygraph, and was quicker and more likely to give a reliable result, Mr Thompson said.

Twenty per cent of people who take a polygraph test show no result, with an 80-85% accuracy rate compared with a 97% accuracy rate for the CVSA.

It is also less "intrusive" than the polygraph, which involves being wired up from various parts of the body. The CVSA involves only a microphone.

The CVSA technology is strictly controlled with vetting procedures to make sure it cannot fall into the hands of those who would use it to expose undercover agents.

Mr Thompson said in one local case in which $US60,000 had gone missing from a firm, all 10 staff denied any knowledge and there was no evidence at all.

"On a wing and a prayer with a couple of damn good interviewers you can sometimes 'get a cough,' as we all know. Not this time. Police and private had failed to get any admissions."

"Tension in the workplace was incredibly high. Morale was low - there was a feeling of mistrust and suspicion by all of the employees."

With their permission Mr Thompson put all parties on the CVSA - nine of the suspects were cleared within five hours. One suspect failed the test and within six hours all the money had been recovered. The person was arrested and made a full statement to the police.

Lie-detector tests are not admissible as evidence but Mr Thompson said he believed the CVSA tool could save New Zealand millions of dollars in police investigation hours: "It's going like wildfire in the US."

One police detective said it was worth considering. "If we have not looked at them perhaps we should be - if it is properly used it can be a useful tool in certain types of investigation," a police detective said.

But police national headquarters officer in charge of investigative support Harry Quinn said police had considered using lie detectors in 1997 but rejected the idea.

Police could not justify the expense, Detective Inspector Quinn said. "They would not be used that frequently."

But he said police were regularly briefed on new equipment.

Comments from our readers

On 10 June 2011 at 3:58 pm Karin Daniel said:

I cannot understand that a first world country like New Z ealand has not used this method of conviction yet. it will save some much time and money.