Technology: Lie detector that listens carefully

Should politicians and errant husbands worry? An Israeli company has developed a software package which it claims can detect when people are lying, based on tiny variations in frequency of the voice called "microtremors". Called Truster, the package is based on the suggestion that when you know you're lying, the blood vessels leading to the larynx involuntarily constrict, making your voice waver - though not at a frequency the human ear can directly detect.

The company claims that it can work even over a telephone connection, and can detect the difference between surprise, a false statement, "avoidance" and truth.

However, when independent testers tried it earlier this week to analyse Bill Clinton's State of the Union address, the software decided that he was telling the truth - though the nervous politician who preceded him, making his first major TV network speech, was lying through his teeth.

Clearly politicians have more control over their larynxes than the company expected. However, its developer, Amir Leiberman, forecasts it will more generally be used by insurance and credit card companies trying to detect tricksters and fraudulent claims. It was originally developed as a screening technology for sensitive military bases to prevent crime and terrorism. It costs roughly pounds 100.