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In order to understand Vago-sympathetic voice stress analysis, one needs to know that stress, when accompanied by guilt and a known consequence, will cause the body to physically react.

Everyone has experienced stress as related to deception at some point in their life.  Whether being accused as a child with regards to stealing from a department store: questionable Internal Revenue Service filings or perhaps even a fidelity issue, stress with any consequence of discovery will manifest itself demonstratively.

This stress can be overtly revealed in the form of observable reactions such as sweating, a shaky voice, dry mouth, increased body odor, runny nose, upset stomach, hives or coupled with notable body movements; i.e. body language. This overt response is commonly referred to as the "Fight or Flight Syndrome." The expression of stress however, is also more latent.

Since the Central Nervous System supports the Autonomic (Uncontrollable) branch, these latent emotions of stress will manifest in a recordable way and cannot be controlled.

The Nervous System

The Central Nervous System, brain and spinal cord integrate informational data via a myriad of sensory neurons. One such neuron is the vagus nerve.

The vagus nerve is a remarkable nerve that relates to the function of numerous structures in the body. The vagus nerve supplies nerve fibers to the pharynx (throat), larynx (voice box), trachea (windpipe), lungs, heart, esophagus and most of the intestinal tract (as far as the transverse portion of the colon. And the vagus nerve brings sensory information back from the ear, tongue, pharynx and larynx.

The Parasympathetic and Sympathetic Branches

The Para-Sympathetic branch of our nervous system comes into play under conditions of normalcy or homeostasis, keeping things more in balance. The Sympathetic branch becomes more involved when "Fight or Flight" becomes an issue. Since this will occur in part below our threshold of awareness, even the most accomplished liar will be unable to hide their Psycho-physiological (mind and body) stress reactions provided there is a clear consequence if discovered.


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Sensory Input

VIPRE was engineered to capture the changes in an individual's vocal responses based on carefully designed question formatting and direct questions that require an absolute affirmation or denial with regards to the consequence of an event or accusation. When the brain receives and interprets information from the questions asked, this information may or may not produce a higher level of stress, depending on guilt, associated with the consequence of discovery. Once any stressful information is learned, the brain sends a message through neurons to effecter cells, muscle or gland cells which react accordingly in a proportionate reaction. The Vagus Nerve picks up this subtle reaction when stress is present by sending motor impulses to the vocal cords (folds). A trained examiner formulates questions to illicit these responses and VIPRE records the utterance in a sound picture or pattern. These patterns are automatically modulated and serve as a visual review of stress or a lack of stress to the direct questions asked in regards to the issue at hand or case under investigation.


In the past, scientists often refer to lie detection as Psycho-physiological Detection of Deception or PPD. Conversely, stress can be recorded and that fact has been documented in numerous scientific and medical studies. As well, scientific and medical studies are rife with support of the Vagus Nerve and its relationship to the brain, psychological, and the body (nerves), physiological. VIPRE in the hands of a competently trained examiner following the manufacturer's recommended guidelines, will add a powerful tool to the available resources at the operators disposal. This is backed by over thirty years of success in voice stress examination coupled with empirical data and anecdotal reports by countless law enforcement agencies.

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