Detection of Emotional Stress by Voice Analysis

A study was performed to develop a methodology for determining emotional stress by voice analysis. Tape recordings of 58 subject examinations for actual or staged criminal offenses were electronically processed. The result of this processing was a measure value for the ratio of the amplitudes of the 100-120 Hz to the 600-800 Hz ranges in each subjects spoken response. A methodology for assessing the measure values to determine the relative levels of stress in these responses was developed. A portable prototype voice analyzer was built which electronically processes a voice signal from either a tape recorder or microphone input. An interrogation and assessment protocol similar to the Zone of Comparison technique used by many polygraph specialists was developed and used to assess the guilt or innocence of five subjects undergoing Zone of Comparison tests. A 95 confidence level was achieved for four of the five subjects.