Two of the most popular stress-detection techniques (the Psychological Stress Evaluator (PSE) and the Voice Stress Analyzer (VSA)) have been considered in the design of this device, as it is a well-known fact that lying is generally associated with an increased level of stress. It is also quite user-friendly, because all the user has to do is turn it on, the readings being then displayed by an LED band so that the results can be measured and analyzed through a bar graph comparator.
The built-in "result indicator" provides an instant display of truthfulness. In addition to the continuous measurement of a person's speech pattern, the Truth Detector analyzes its own data to give you cumulative results.
According to the manufacturers' statements, the company Laguna, testing can be done from conversations on the radio, television, and even tape recordings. But there's no such device that can be considered completely flawless, and the manufacturers admit this situation. Moreover, they even recommend the use of the device in an area where no background noise is present, as it can affect the readings' accuracy.