| Voice Stress Analysis |
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Voice stress analysis is a controversial technology that attempts to examine and measure a Physiological Stress component, by extracting micro tremors from the voice of a person and measuring their Amplitude . Voice stress analysis of often applied as a type of Lie Detector . APPLICATIONS The purpose in measuring voice stress is to attempt to determine the truthfulness of responses by an examinee regarding the subject of investigation. These measurements are made by analyzing the "stress level," or agitation, of the subject and using it as a guide to predict a physiological relation to responses given, based upon the reasoning that high levels of stress suggest the examinee is lying. The amplitude of vocal tremors can be measured in Hertz by an analysis device; a low stress is implied at approximately ten Hertz , and a high level of stress would correspond to a lower level signal. Since every person is presumed to produce different levels of voice stress according to their own physiology, some significant variation in measurement and interpretation is necessary. Also, unlike a traditional lie detector, with which simple "yes" or "no" answers are given to questions, longer answers are needed for sufficient material to make analyses from. Devices used to analyze voice stress are sometimes used in the presence of the individual under investigation; however, they can also be used without his or her knowledge. Since all that is needed is a voice, a Wireless Microphone , a Telephone connection, or even a tape recording can provide the necessary input signal. During the analysis process, it is possible irrelevant or collateral subjects also be discovered, leading to false readings. Because analyses are subjective, the actual use of voice stress as a determinant of truth is unreliable. USES IN LAW ENFORCEMENT A great deal of voice stress testing has been conducted. The Israeli Intelligence community is often cited as major users of this technology. In the United States, most private use of these devices has been made illegal. However, the CIA and FBI , both instrumental in the creation of these devices about 30 years ago, continue to employ them at times in their own investigations. |
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