Since the earliest days of civilization, people have been faced with the problem of figuring out who's lying and who's telling the truth.
To help determine that, truth seekers throughout the years have developed many methods to gauge a suspect's guilt or innocence. Most of those methods relied on physiological indicators such as sweating, rapid pulse rates, blushing, rapid breathing, trembling, or shifting gazes.
During the 1960s, the American military sponsored research to develop a convert lie detector.
Methods ranged from using optical scanners to measure pupil dilation, infrared scanners to monitor skin temperature, microwave interferometers to measure breathing, and even odor detectors. Also during that period, some research was directed at detecting stress levels in voice.
It seems that a person's voice changes under stress. In rare instances, a voice can even "crack". Such changes make voice-stress analysis possible. Best of all, as hinted at earlier, a test subject need not be present; conversation taken from a radio, television, telephone, or even tape recording can be used.
In the mid sevnties, American scientists developed the psychological Stress Evaluator (PSE) and the Voice Stress Analyzer (VSA). Daka Research has taken these two prominent principles and developed the Truth Machine. The Truth Machine detects the resulting frequency modulation produced by micro tremors and at the same time it measures the amplitude of upper and lower sidebands from voice modulations. The result can be analyzed through the bar graph comparator as shown visually by the LED band.
It is a fun novel and make a great conversation piece. Test it with TV personalities, actors in film newscasters, politicians, and your friends. Evaluate yourself to see if you sound calm and confident.
Shown here is a small portion of a linear plot of Received Signal Strength Indicator (RSSI) response. Note that the slope or gain around small-input-signal-point P1 is high while the gain for a larger signal at a higher point, P2, is smaller.