Voiceprint, a visual representation of a person's voice used for purposes of identification. A voiceprint is made with a sound spectrograph, a device used to analyze complex sound waves. The voiceprint appears as a pattern of tracings that indicate the moment-by-moment distribution and relative strengths of a voice's component frequencies. The voiceprints of different people speaking the same words generally show patterns unique to each speaker. Unlike fingerprints, however, voiceprints made at different times (of the same person speaking the same words) may show some variation. Voiceprints were first used as evidence in a court of law in 1966.
A SWAT (Special Weapons and Tactics) team is an elite unit within a police force, used for exceptional situations that require increased firepower or specialized tactics. Find out how SWAT team members train, what gear they use and how they conduct raids.
A hostage situation places innocent civilians directly in harm's way, and armed intervention places the hostages at even greater risk. Learn how a skilled negotiator uses psychology, instinct and deception to achieve a peaceful end.