Voice stress analysis
Encyclopedia
Voice Stress Analysis technology is said to record psychophysiological stress responses that are present in human voice, when a person suffers psychological stress in response to a stimulus (question) and where the consequences may be dire for the subject being 'tested'.
In the Detection Of Deception (DOD) scenario, the voice-stress produced in response to a Relevant Question ("did you do it?") is referred to as psychological stress or 'deceptive stress'. No DOD technology can detect a lie or truth unequivocally. It is the fear of being exposed to the question being posed that produces the 'high stress' voice signature, aka voice graph or voice tracing.
The technique's accuracy remains debated. There are independent research studies that support the use of VSA as a reliable lie detection
technology, whilst there are other studies that dispute its reliability.
There is tension between the voice stress analysis community and the polygraph
community, due in the main to the fact that the polygraph is heavily regulated and has been subject to numerous detailed scientific studies, while voice stress analysis is largely unregulated and there are few studies (other than by manufacturers and proponents) which show results better than chance
.
The main difference in the method of operation between LVA and VSA is based on the analyzed frequencies ranges: while VSA focuses on the 8–14 Hz range (which is picked up by specialised microphones), LVA uses a wider spectrum range to extract information that is amusing but not particularly relevant to DOD.
. The experiment was made by attaching electrodes to the cricothyroid muscle
and the posterior cricoarytenoid muscle
and measuring EMG
signals. Detecting microtremor during sustained speech was not deemed possible because the EMG activity changed too rapidly. The experiment was therefore limited to measuring the presence of microtremor in the frequency range of 1 through 20 Hz in sustained vowel phonation, but yielded no positive results. It was concluded that "the electrical energy was randomly distributed throughout the spectrum." The inconclusive research on microtremor in voice production has consequently been used to claim that the phenomenon can be used for creating technology capable of lie detection by detecting microtremor in recorded speech.
Vendors=
The original VSA technology was devised by three former US Army personnel. The three, Bell, McQuiston & Ford, developed the PSE 1, an analogue machine. The same three, working under Dektor Counterintelligence and Security Inc.
, manufactured the PSE 1000 and later the PSE 2000.
The National Institute Of Truth Verification (NITV, West Palm Beach) then produced and marketed an analogue instrument based on the PSE & digitized it in April 1997, based on the McQuiston-Ford algorithm. In the past 10 years VSA has been used primarily in digital applications: Digital Voice Stress Analysis (D-VSA). The primary suppliers worldwide are: NITV(USA)-CVSA; POLYVSA(TVT Centre RSA)- AVSA PRO 1,8. Older manual systems are supplied by TDT (previously known as Diogenes Lantern); Expertos and PSE 5128.
The primary use of VSA is in the arena of "Detection Of Deception". As with the polygraph, VSA technology is inert. It has no artificial intelligence component. It is the use of the recorded data as a means for lie detection that remains controversial.
Another interesting application used by the Italian State Police, the International Crime Analysis Association and other law enforcement agencies worldwide, law firms, journalists and professional investigators is the X13-VSA Voice Stress Analyzer http://www.lie-detection.com
High levels of (deceptive) stress indicate that the examinee is deceptive as is the case with polygraph. In respect of VSA, squared voice grams indicates higher stress, whilst 'wave form' or 'domed' signatures indicate less stress.
Questions may be posed to elicit simple "yes" or "no" answers, but can be posed to produce a narrative response. Questions are formulated for each individual being examined to compare situational stress signatures with Control Question and Relevant Question signatures, in order to identify (deceptive) 'stress signatures'.
VSA technology together with validated testing protocols, is designed to protect the innocent and avoid 'false positive' results. VSA is designed to assist any investigation by establishing the veracity of a subject's verbal responses.
Devices used to analyze voice stress are usually 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
or a tape recording can provide the necessary input signal.
There are no known physical countermeasures for VSA. Conversely according to Honts et al., the simple use of a 'tack' placed under the tongue of the examinee, to be used as a countermeasure, can reduce the accuracy of polygraph results from 98% to 26%.
Many intelligence agencies as well as private forensic psychophysiologists worldwide utilise VSA in preference to polygraph technology.
.
Polygraph-only associations have disputed the accuracy of VSA, although many accredited polygraphists have trained in the use of VSA and use VSA to good effect. The traditional analysis and scoring of voice-grams by means of assigning 'percentages' is time consuming.
In 2002, Clifton Coetzee (Polygraph & VSA Instructor) devised a scoring method for voice grams incorporating the 'UTAH 7 Point' scoring system, as used by modern day polygraphists. Reactive or Responsive patterns are assigned a weighting of +3 to -3.
The use of CQT testing protocols developed by John Reid and Cleve Backster are used for greater reliability of VSA results. It is important that VSA examiners be skilled in the use of enforced, timed pauses between stimulus (question) and response (answer). As in the polygraph situation, the fight or flight response has onset and conclusion delays, which must be considered by examiners to achieve reliable results.
In 2010 through to 2011, Clifton Coetzee and Jean-Louis Gouin (Alpes-Software: Developer of original Diogenes Lantern, which is now re-labelled as TDT )developed AVSA PRO, which is a unique, evolutionary, fully automatic VSA system. AVSA PRO is programmed to cater for cadence control being consistent in every question posed. Examiner induced errors have been eliminated. AVSA PRO is based on a neural network - another major innovation in the worldwide vsa industry. Scoring of automatically captured and numerically identified voice wavs is according to the neural network database, developed from Expert blind scoring of 000's of voice wavs, with the input of known outcomes.
The American Polygraph Association's website lists conclusions from multiple studies, intended by the polygraph industry to discredit vsa, into the accuracy of voice stress analysis as a means of detecting the subject's truthfulness. Some researchers or polygraph professionals cast doubt on the validity of the results of such tests; many describe the results as no better than chance.
The National Academy of Sciences (USA) severely criticized the validity of APA studies into polygraph as "biased, unscientific and industry funded." The NAS study concluded that there has been no scientific advancement in polygraphy. Further, that polygraphy was unreliable as a lie detection technology. ( http://www.nap.edu/openbook.php?isbn=0309084369 )
In the Detection Of Deception (DOD) scenario, the voice-stress produced in response to a Relevant Question ("did you do it?") is referred to as psychological stress or 'deceptive stress'. No DOD technology can detect a lie or truth unequivocally. It is the fear of being exposed to the question being posed that produces the 'high stress' voice signature, aka voice graph or voice tracing.
The technique's accuracy remains debated. There are independent research studies that support the use of VSA as a reliable lie detection
Lie detection
Lie detection is the practice of attempting to determine whether someone is lying. Activities of the body not easily controlled by the conscious mind are compared under different circumstances. Usually this involves asking the subject control questions where the answers are known to the examiner...
technology, whilst there are other studies that dispute its reliability.
Criticism
Voice stress analysis has been described as pseudoscientific, and there is no known scientific basis for the underlying theory of "microtremors". Federally funded research in the United States showed "little validity" in the technique. A study by Virginia State in 2003, at which time the technique was in widespread use, concluded that "Because there have been no independent scientific studies conducted on the reliability of the computer voice analyzer to detect deception, the Board recommends to the Director of the Department of Professional and Occupational Regulation that computer voice analyzer equipment should not be approved in Virginia at this time.", though a number of academic studies are available which call into question the validity of the techniqueThere is tension between the voice stress analysis community and the polygraph
Polygraph
A polygraph measures and records several physiological indices such as blood pressure, pulse, respiration, and skin conductivity while the subject is asked and answers a series of questions...
community, due in the main to the fact that the polygraph is heavily regulated and has been subject to numerous detailed scientific studies, while voice stress analysis is largely unregulated and there are few studies (other than by manufacturers and proponents) which show results better than chance
Randomness
Randomness has somewhat differing meanings as used in various fields. It also has common meanings which are connected to the notion of predictability of events....
.
VSA vs LVA
VSA is distinct from Layered Voice Analysis (LVA). LVA is used to measure many different components of the voice, but is not reliable in the detection of 'deceptive stress'. LVA measures a wide range of emotions, including excitement, confusion, attention and more. LVA is available in many different forms of products, ranging from server based intelligence use systems, to hand-held devices and standard PC software.The main difference in the method of operation between LVA and VSA is based on the analyzed frequencies ranges: while VSA focuses on the 8–14 Hz range (which is picked up by specialised microphones), LVA uses a wider spectrum range to extract information that is amusing but not particularly relevant to DOD.
Principle and origins
VSA is based on hypothesis that there are infrasonic components of human voice not audible to observers caused by a physiological phenomenon present in muscles called "microtremor". It was discovered in 1957 by British physiologist Olaf Lippold. Further investigation by other researchers explored the possibility of the presence of microtremor in the muscles controlling the voiceboxLarynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
. The experiment was made by attaching electrodes to the cricothyroid muscle
Cricothyroid muscle
The cricothyroid muscle is the only tensor muscle of the larynx, aiding with phonation. It attaches to the anterolateral aspect of the cricoid and the inferior cornu and lower lamina of the thyroid cartilage, and its action tilts the thyroid forward to help tense the vocal cords...
and the posterior cricoarytenoid muscle
Posterior cricoarytenoid muscle
The posterior cricoarytenoid muscles are extremely small, paired muscles that extend from the posterior cricoid cartilage to the arytenoid cartilages in the larynx. By rotating the arytenoid cartilages laterally, these muscles abduct the vocal cords and thereby open the rima glottidis. Their action...
and measuring EMG
Electromyography
Electromyography is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph, to produce a record called an electromyogram. An electromyograph detects the electrical potential generated by muscle...
signals. Detecting microtremor during sustained speech was not deemed possible because the EMG activity changed too rapidly. The experiment was therefore limited to measuring the presence of microtremor in the frequency range of 1 through 20 Hz in sustained vowel phonation, but yielded no positive results. It was concluded that "the electrical energy was randomly distributed throughout the spectrum." The inconclusive research on microtremor in voice production has consequently been used to claim that the phenomenon can be used for creating technology capable of lie detection by detecting microtremor in recorded speech.
Vendors=
The original VSA technology was devised by three former US Army personnel. The three, Bell, McQuiston & Ford, developed the PSE 1, an analogue machine. The same three, working under Dektor Counterintelligence and Security Inc.
Dektor Counterintelligence and Security Inc.
Dektor Counterintelligence and Security Inc. was a company started by Allan D. Bell Jr, President, Charles McQuiston, Vice President, Wilson Henry Ford, Vice President of Research and Development, in Springfield, Virginia around 1969-70...
, manufactured the PSE 1000 and later the PSE 2000.
The National Institute Of Truth Verification (NITV, West Palm Beach) then produced and marketed an analogue instrument based on the PSE & digitized it in April 1997, based on the McQuiston-Ford algorithm. In the past 10 years VSA has been used primarily in digital applications: Digital Voice Stress Analysis (D-VSA). The primary suppliers worldwide are: NITV(USA)-CVSA; POLYVSA(TVT Centre RSA)- AVSA PRO 1,8. Older manual systems are supplied by TDT (previously known as Diogenes Lantern); Expertos and PSE 5128.
The primary use of VSA is in the arena of "Detection Of Deception". As with the polygraph, VSA technology is inert. It has no artificial intelligence component. It is the use of the recorded data as a means for lie detection that remains controversial.
Another interesting application used by the Italian State Police, the International Crime Analysis Association and other law enforcement agencies worldwide, law firms, journalists and professional investigators is the X13-VSA Voice Stress Analyzer http://www.lie-detection.com
Applications
The purpose of a VSA examination is to determine the truthfulness of responses made by an examinee regarding the subject under investigation. Determinations are made by analyzing and scoring the voice-grams produced by the examinee. Traditional analysis of voice grams was achieved by allocating "percentages of stress" ( % ) according to the patterns so produced.High levels of (deceptive) stress indicate that the examinee is deceptive as is the case with polygraph. In respect of VSA, squared voice grams indicates higher stress, whilst 'wave form' or 'domed' signatures indicate less stress.
Questions may be posed to elicit simple "yes" or "no" answers, but can be posed to produce a narrative response. Questions are formulated for each individual being examined to compare situational stress signatures with Control Question and Relevant Question signatures, in order to identify (deceptive) 'stress signatures'.
VSA technology together with validated testing protocols, is designed to protect the innocent and avoid 'false positive' results. VSA is designed to assist any investigation by establishing the veracity of a subject's verbal responses.
Devices used to analyze voice stress are usually 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
Wireless microphone
A wireless microphone, as the name implies, is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated...
or a tape recording can provide the necessary input signal.
There are no known physical countermeasures for VSA. Conversely according to Honts et al., the simple use of a 'tack' placed under the tongue of the examinee, to be used as a countermeasure, can reduce the accuracy of polygraph results from 98% to 26%.
Use In law enforcement
A great deal of voice stress testing (VSA) has been conducted. In the United States, most states do not regulate the private use of these devices. However, the CIA and FBI both use VSA at times, in their own investigations. The technology is currently recognized in 43 states.Many intelligence agencies as well as private forensic psychophysiologists worldwide utilise VSA in preference to polygraph technology.
.
Methodology and accuracy
The McQuiston-Ford algorithm used for Voice Stress Analysis is reliably accurate. The recorded "micro tremors" in a persons voice are converted via the algorithm into a scorable voice gram. The discrepancy in researched accuracy may result from incorrectly trained or non-trained persons utilizing the technology incorrectly. This is evident by some Polygraphists trying to "test" VSA technology without having received accredited training in the use thereof also by applying Poly Protocols to VSA & vice versa which cannot work.Polygraph-only associations have disputed the accuracy of VSA, although many accredited polygraphists have trained in the use of VSA and use VSA to good effect. The traditional analysis and scoring of voice-grams by means of assigning 'percentages' is time consuming.
In 2002, Clifton Coetzee (Polygraph & VSA Instructor) devised a scoring method for voice grams incorporating the 'UTAH 7 Point' scoring system, as used by modern day polygraphists. Reactive or Responsive patterns are assigned a weighting of +3 to -3.
The use of CQT testing protocols developed by John Reid and Cleve Backster are used for greater reliability of VSA results. It is important that VSA examiners be skilled in the use of enforced, timed pauses between stimulus (question) and response (answer). As in the polygraph situation, the fight or flight response has onset and conclusion delays, which must be considered by examiners to achieve reliable results.
In 2010 through to 2011, Clifton Coetzee and Jean-Louis Gouin (Alpes-Software: Developer of original Diogenes Lantern, which is now re-labelled as TDT )developed AVSA PRO, which is a unique, evolutionary, fully automatic VSA system. AVSA PRO is programmed to cater for cadence control being consistent in every question posed. Examiner induced errors have been eliminated. AVSA PRO is based on a neural network - another major innovation in the worldwide vsa industry. Scoring of automatically captured and numerically identified voice wavs is according to the neural network database, developed from Expert blind scoring of 000's of voice wavs, with the input of known outcomes.
The American Polygraph Association's website lists conclusions from multiple studies, intended by the polygraph industry to discredit vsa, into the accuracy of voice stress analysis as a means of detecting the subject's truthfulness. Some researchers or polygraph professionals cast doubt on the validity of the results of such tests; many describe the results as no better than chance.
The National Academy of Sciences (USA) severely criticized the validity of APA studies into polygraph as "biased, unscientific and industry funded." The NAS study concluded that there has been no scientific advancement in polygraphy. Further, that polygraphy was unreliable as a lie detection technology. ( http://www.nap.edu/openbook.php?isbn=0309084369 )