Truth Detector detects voice stress patterns and glows red when it hears someone saying ‘of course I’ll give it back’. $39.99. Two of the most effective indicators are the Psychological Stress Evaluator (PSE) and the Voice Stress Analyzer (VSA). These tests have been imported into the Truth Detector, a specially designed device that analyzes and measures the frequency changes that occur in the voice when a person undergoes stress. The machine’s detections are then displayed by an LED band so that the results can be measured and analyzed through a bar graph comparator.