Reliability and validity of an interval measure of vocal stress.

The reliability and validity of Psychological Stress Evaluator (PSE) output and frequency modulation suppression as an inaudible vocal measure of stress-arousal was further explored, using a new interval scoring method. 'Yes' answers to 6 neutral questions were obtained from 106 volunteers 2 weeks before, the day before and one week after a stress-provoking event (oral comprehensive examinations for an MS degree). The data show excellent construct validity and good but not high internal consistency (0.77-0.81) and test-retest (0.72-0.74) reliability. Interrater reliability ranged from 0.94 to 0.98. Correlations of PSE output with other psychological and physiological measures (criterion-related validity) was very poor.