Telephone lie detector claims to catch fibbers

A new telephone lie detector system promises to pick up on tell-tale signs of stress in a caller's voice whenever they tell a fib.

Available for free, the Kishkish lie detector can be easily downloaded from the web and used by those who make phone calls over the internet.

More:

• Time magazine's Person of the Year is... you!

• X Factor winner Leona set for fastest Christmas number one

• Great viral emails to make you giggle

• More Science & tech news

Scientists have found that frequencies in the human voice are sensitive to honesty, becoming higher when a person is lying.

This is because in moments of stress, such as telling a lie, our muscles tighten as our body prepares to flee or fight causing the pitch of our voice to alter.

The inventors of the lie detector claim the software mimics police technology by monitoring the stress levels of the person speaking on the phone to judge whether they are telling the truth.

Already 320,000 people have downloaded the lie detector system. Using the infamous example of Bill Clinton's denial about his relationship with Monica Lewinsky, the developers show on their website a graph which rises as he utters the lie: 'I did not have sexual relations with that woman.'

The software measures stress levels between one and 100, with a green light which shows when stress levels are normal, which then changes to red when they rise to high, allowing the user to gauge whether the other person is lying.

Many police forces across America use the controversial technology when interviewing crime suspects, and it has also been used by the US military in the 'war on terror'.

The lie detector is currently available for those who make calls using Skype technology.

Skype, which has over 100 million registered users worldwide, is one of the best known of several internet-based phone systems which allow callers to make free calls around the world.

Using the communication software, calls to other computers are free, while other calls to landlines are charged at around 1p a minute.

Paul Amery, director of Skype developer program, said: 'This is a really neat application, and the kind of thing we want to see more of. The Kishkish team has managed perfectly to integrate this unique application to meet the needs of our clients.'

'Lie detector is the latest in a variety of products in our premium add-on program which greatly enhance the Skype communication experience. Extras are all about helping end users do more with Skype, and this will certainly encourage it,' said Dr Zvi Marom from the programmes makers, BATM.

'We are delighted to be able to introduce this unique software to Skype's premium offering and will continue to work closely with them to develop new software-based communication applications.'