Abstract

The Air Force Research Laboratory (AFRL) has been asked by the National Institute of Justice to investigate voice stress analysis (VSA) technology and evaluate its effectiveness for both military and law enforcement applications. This technology has been marked as commercially available in computer based form, and marketed as being capable of measuring stress and, in some systems, deception. This technology is reported to be easier to use, less invasive and less constrained in its operation than standard polygraph technology. This study has found the VSA technology can identify stress better than chance with performance approaching that of current polygraph systems. However, it is not a technology that is mature enough to be used in a court of law. We also found that experience and training improve the accuracy than less trained individuals. Lastly, we explored how this technology may become an effective interrogation tool, when combined with polygraph technology. This article contains information and results of a primary work done to show how the stress changes for Mel Frequency Cepstral Coefficient features can be detected through FFT signal processing when a person is under psychological pressure. The principal purpose is to obtain a tool that could help the accused to prove their innocence in an offense or a crime.

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