The Future of Lie Detection: Computer Voice Stress Analysis v. Polygraph


The heightened pace of the digital age is rapidly transforming lie detection reliance from the mostly commonly  used testing, polygraph, to computer-based voice stress testing (CVSA).

According to SpeechTechMag,

“Nearly 1,800 U.S. law enforcement agencies have dropped the polygraph in favor of newer computer voice stress analyzer (CVSA) technology to detect when suspects being questioned are not being honest, according to a report from the National Association of Computer Voice Stress Analysts.

Among those that have already made the switch are police departments in Atlanta, Baltimore, San Francisco, New Orleans, Nashville, and Miami, FL, as well as the California Highway Patrol and many other state and local law enforcement agencies.

In one of the most famous uses of  CVSA, after the fatal shooting of Floridian Trayvon Martin by George Zimmerman, Zimmerman was given a voice stress analysis test by the police department of Sanford, Florida. He passed the test.  A videotape of the test was publicly released in June 2012.

How does Computer Voice Stress Analysis work?

In a nutshell, CVSA works by measuring involuntary voice frequency changes that would indicate a high level of stress, as occurs when someone is lying. Muscles in the voice box tighten or loosen, which changes the sound of the voice, and that is what the CVSA technology registers.  The first CVSA devices came on the market in 1988.

(In contrast, the polygraph measures and records several physiological characteristics, such as blood pressure, pulse, respiration while the subject responds to a series of questions. The technology was developed in 1921.)

Who uses CVSA?

Employers, law enforcement, litigators and others with a vested interest in establishing the veracity of information or testimony.

How reliable is CVSA?

An 18 year study conducted by Dr. James L. Chapman, Professor Emeritus, Former Director of Forensic Crime Laboratory, State University of New York at Corning, evaluated the use of the Voice Stress Analysis technology for the detection of stress associated with possible deception. Using a combinatorial approach of VSA and a standardized questioning process, Dr. Chapman was able to show that VSA detected stress associated with criminal activities in 95% of the confession obtained cases studied. Dr. Chapman found no cases wherein a confession was obtained in the absence of stress. In particular, the most considerable stress levels were detected during the investigation of murder, grand larceny and sexual crimes. Dr. Chapman identified that when VSA is utilized as an investigative decision support tool in accordance with required operating procedures, and standard VSA interviewing techniques are employed, elicited confessions from criminal suspects can strongly be predicted based upon results of their VSA examinations. Further, VSA can be used by trained professionals to support the acquisition of court admissible criminal confessions at a rate superior to other legal interrogation methods currently employed by the criminal justice system

Source: Wikipedia

How does the court view CVSA?

A U.S. federal court in the Northern District of New York in early March, 2014 ruled that sex offenders can now be required to submit to CVSA examinations as part of their post-release supervision.

Why CVSA rather than polygraph?

  • Units can be carried into the field. The technology can be brought to the suspect rather than having to take the suspect to the technology.
  • Training is required to operate the CVSA, but the training is not nearly so expensive or so extensive as that required for a licensed polygraph examiner.
  • The changes in voice detected by the CVSA occur simultaneously with the speech, not in a delayed fashion as with the polygraph.
  • The CVSA is less physically intrusive. The suspect is not strapped down and wired.
  • The equipment itself is less expensive than a polygraph machine.

All in all, we see CVSA technology as the future of lie detection.

BNI Operatives: Situationally aware.

As always, stay safe.

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