Voice analysis for detection of deception

Human voice can signal the psychological state of an individual. Be it emotional, physical, intentional or unconscious, voice reveals the internal state of the speaker. Therefore, the main aim of the present study is to identify which voice parameter could be used as a reliable indicator of stress due to deception. For analyzing real life natural stress, the voice of crime suspects was recorded during ongoing interrogations at the police station. PRAAT software was used for analysis. Results indicated a significant increase in the mean fundamental frequency (F₀) and formant frequencies F1, F2. Marginal decrease in jitter was observed, however, shimmer did not at all correlate to stress due to deception. Pitch contours indicated considerable rise in the pitch of crime suspects while answering specific direct questions. Thus, it was concluded that mean F₀ and formant frequencies F1, F2 correlate strongly to stress.