It used to be that detecting a lie depended upon the observer’s experience and
intuition. Then, along came the polygraph—an
instrument that, for 60 years, helped detect the veracity of someone. The
polygraph had some effectiveness, but it also had its problems and limitations.
New technology has made possible an innovative entry into the field of lie
detection—the Computer Voice Stress Analyzer® (CVSA
). Developed in the 1980s,
this relatively new technology features the recording, quantifying and analyzing
of the subject’s voice. By 1989, CVSA was making its first inroads in law
enforcement, primarily with smaller police agencies.
effectiveness quickly prompted some large metropolitan agencies to add its
technology. Those agencies now include Atlanta, Miami, Nashville, New Orleans,
and the California Highway Patrol. In addition, the CVSA® and CVSA®II have been
used in military combat and field conditions by the U.S. military since
the National Institute for Truth Verification Federal Services™ (located in
West Palm Beach, Fla.) that is the manufacturer and sole source of CVSA and
CVSA II and the “Final Analysis Confirmation Tool™” (FACT™). FACT is a patented
and validated automated scoring algorithm for quantifying and evaluating voice
II is the “next generation” model that adds the FACT Scoring System; a
simplification of the examiner interfaces to reduce the time required in
conducting examinations. The CVSA II has the capability to record live and
telephonic examinations onto the system’s hard drive.
voice stress analysis is low in cost, and the technology to use it is easy to
operate and adaptable to various conditions. But its hallmark seems to be its
accuracy. A recent study by James Chapman in the annual scientific journal,
“Criminalistics and Court Expertise,” states that the accuracy of computer
voice stress analysis is greater than 95 percent.
study was based on an 18-year field study. Chapman is not alone in his
assessment. Journalist Bob McCarty, author of “The Clapper Memo,” tells of the
failures of the polygraph—failures that sometimes allowed circumstances leading
to insider attacks against members of the U.S. military in Afghanistan.
polygraph, the subject of computer voice stress analysis is not “wired to” an
instrument when undergoing an examination. Only a microphone is used, which is
plugged into the computer to analyze the subject’s responses. As the subject
speaks, a voice pattern is displayed and numbered, and saved to a chart to
medical problems do not affect the results of the examination, and there are
really no “counter measures” that could cause an inconclusive result such as
those that occur with a polygraph. The computer voice stress analyzer notes the
frequency changes in the subject’s voice and “identifies” the vocal stress
related to the specific facts under investigation.
computer processes the voice frequencies and displays a graph “picture” of them. There is no need for strictly “yes” or “no”
answers, and the computer process can “follow” unstructured conversation,
recorded conversations, and live telephone conversations.
tremors are tiny frequency modulations in the human voice and, when a subject
is lying, the automatic or involuntary nervous system causes inaudible changes
in those micro tremor frequencies. The computer voice stress analyzer detects,
measures, quantifies and displays those changes in a graph format that can be
evaluated and quantified for stress.
technology is digitized and incorporated into a multi-functional notebook
computer that is easily carried and that also has FAX and e-mail capability for
the sending of charts for cold call review by other examiners. When used with
the National Institute for Truth Verification’s interviewing and interrogation
techniques, results appear quite quickly (average examination time is 40
minutes) and the results can be very accurate in identifying deception or in
to Chapman’s study, the consequence-based stress detected in the human voice
when using a computer voice stress analyzer directly correlates to the matters
of truth and deception. The analyzer is said to have an error rate of less than
one-half of 1 percent.
National Association of Computer Voice Stress Analysts (NACVSA
) represents a
membership of about 2,000 U.S. law enforcement agencies and thousands of criminal
justice professionals. It is exclusively associated with computer voice stress
analysis examiners, and the organization hosts continuing education and
professional development programs, monitors legislation impacting CVSA, and
administers a professional certification program. The NACVSA feels that the
CVSA proves its accuracy—and the polygraph an error-prone status.
has offered training in voice stress analysis since 1980. Its instructors are
either former law enforcement personnel with experience in voice stress
analysis and polygraph, or they have experience in such specific areas as
interviewing and interrogation.
examiners’ course includes such topics as the history of lie detection, systems
used in the instrumentation technology, the physiology of the body’s reaction
to jeopardy and how those reactions can be monitored, interviewing and
interrogation, the psychological and physiological responses to questions and
the “flight or fight” reaction, chart interpretation, scoring, test
applications and construction, and covert interviewing and subsequent analysis.
for computer voice stress analysis equipment and training can often be gained
through traditional police grant sources such as the Edward Byrne grants in the
U.S. Department of Justice, Wal-Mart’s and Target Corporation’s grants for
local law-enforcement agency equipment purchases, local fraternal and
charitable groups such as American Legion, Veterans of Foreign Wars, Knights of
Columbus, Lions Club, Moose Lodge, etc. Other grant suggestions are given on
the CVSA website.
18-Year Field Study Validates Computer Voice Stress Analyzer as
Most Accurate Truth Verification Technology
Independent, peer-reviewed research has validated the accuracy of
the Computer Voice Stress Analyzer. According to the National Association of
Computer Voice Stress Analysts, a recently published research study in the 2012
annual edition of the scientific journal Criminalistics and Court Expertise
reports the accuracy rate of the (CVSA) is greater than 95%, an assertion long
made by the system’s manufacturer. The study’s results are further bolstered by
current U.S. Government funded voice analysis research, which has established
voice technologies performed well for border security applications.
The 18-year field study was conducted by Professor James L. Chapman
and titled “Long-Term Field Evaluation of Voice Stress Analysis in a North American
Criminal Justice Setting.” Professor Chapman was known as the world’s foremost
authority on the application of Voice Stress Analysis technologies.
Recently deceased, Professor Chapman’s career spanned over 40
years as a criminologist, educator and researcher, during which he conducted
more than 15,000 Voice Stress Analysis examinations. The study’s co-author,
Marigo Stathis, a neuroscientist and research analyst, has been the primary or
co-author of 27 published scientific articles and studies focusing on various
topics related to the human brain and biology.
Professor Chapman used the CVSA to conduct the research and the
results achieved were highly consistent throughout the period the study’s data
were collected. The study’s findings revealed the CVSA, when used as an
investigative support tool, can accurately predict whether a person under
investigation is being truthful or deceptive.
The study’s findings are supported by scientifically accepted statistical
models, and by the 96.4 percent validated confession rate Professor Chapman
attained during the course of the 18-year study. According to current
scientific research and meta-analyses, police confession rates worldwide vary
between 20-45 percent, with even the most experienced police interviewers only
achieving a 50-55 percent confession rate.
Empirical data collected by the CVSA’s manufacturer, U.S. law
enforcement and U.S. military CVSA users have long supported such findings;
however, this is the first independent and peer-reviewed scientific study to
validate these data. Additional studies and research are planned for the