Psychological stress evaluators: EMG correlation with voice tremor

Temporal measurements of frequency changes in the human voice and tremor in the muscles of the vocal area suggest that these phenomena are correlated. A measure of muscular activity was obtained using a non linear filter on the EMG wave. Frequency changes were detected in the third formant of the voice spectrum. The crosscorrelation results indicate that the voice vibrations are forced oscillations generated by central nervous activity, explaining the detection of stress from voice records.