Voice stress analysis
Voice Stress Analysis (VSA) 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'. However, it is not possible to cleanly separate the excitation signal into components due to emotion and those due to deception. Thus no DOD technology can detect a lie or truth unequivocally, but only whether a speaker is experiencing stress. For example, a suspect under questioning would also display natural stress even if he were not guilty.
The technique's accuracy remains debated. There are no independent research studies that support the use of VSA as a reliable lie detection technology, whilst there are numerous studies that dispute its reliability.
In civil court testimony, the CVSA founder, Mr. Charles Humble, testified that "NITV acknowledges that the CVSA is not capable of lie detection and specifically cautions its users regarding proper use of the device."
Air Force Research Laboratory (Haddad et al.) conducted validation studies into VSA and concluded that mainstream VSA (Diogenes and CVSA) as well as polygraph tests are useful in helping trained operators in obtaining confessions by convincing the subject that they cannot deceive the device. As such, it is considered a useful interrogation tool.
Voice Stress Analysis (VSA) remains a controversial lie detection technology. It was described as pseudoscientific. While there is a wealth of scientific basis for the underlying theory of "microtremors," this data is based predominantly upon research on skeletal muscle (i.e. calf, finger). This data has been extrapolated to the muscles that control phonation.
Federally funded research via the American Polygraph Association in the United States showed "little validity" in the technique.
Air Force Research Laboratory conducted validation studies into VSA and concluded that mainstream VSA were useful in focusing investigations and obtaining confessions by convincing suspects that they cannot deceive the machine.
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, contentious scientific studies, while voice stress analysis is largely unregulated. However, there are few studies which show VSA results to be even slightly better than chance.
In Anders Eriksson and Francisco Lacerda's article "Charlatanry in forensic speech science: A problem to be taken seriously" voice stress analysis is described as charlatanry, and that analysis of studies shows that these methods perform at chance levels. They argue that "there are serious ethical and security reasons to demand that responsible authorities and institutions should not get involved in such practices." Not surprisingly, this article meet its own criticisms from manufacturers of voice stress analysis machines. Due to the controversy, the International Association of Forensic Linguists' peer-reviewed journal International Journal of Speech, Language and the Law withdraw the article. However, there have no subsequent studies that refute the findings contained within that article.
VSA vs LVA 
VSA is distinct from Layered Voice Analysis (LVA). Commercial VSA utilizes the inaudible microtremors (range: 6–14 Hz) in the voice to detect high stress in the speaker's words. High stress in situations where there are potentially dire consequences for the speaker is typically defined as Deceptive Stress. The microtremor is a reliable parameter as it is involuntary and cannot be affected by the speaker at will. VSA microtremor DOD was used to a high degree of reliability during the US Vietnam war effort, as an alternative to the time-devouring process of polygraphy. The US Counterintelligence Electronic Division first identified the use of microtremors when using spectrography in covert telephone monitoring operations.
Principle and origins 
VSA is based on the presence of 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 voicebox (Larynx.) 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 conclusive research on microtremor in voice production has consequently been used to develop VSA technologies.
VSA 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 of lying 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 as lying 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. This is equally true for polygraph. The US NAS 2003 study on polygraph threw the polygraph industry into disarray when it reported that studies were unscientific and unreliable and that there was no promise of the technology improving.
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 recorded via an omni-directionalphone. LVA utilises components of the voice such as pitch and tone, which are conrollable by the user, also varying according to his/her emotions at time of utterance. Change of emotions produce unreliable results being not particularly relevant to DOD. .
The original VSA technology was devised by three former US Army personnel from the Counterintelligence Electronic Div. The three, Bell, McQuiston & Ford, developed the PSE 1, an analogue machine. The same three, working under Dektor Counterintelligence and Security Inc., manufactured the Phoenix telephone analyzer, the PSE 1000 and later the PSE 2000.
In 2001, the company X13-VSA Ltd. has released his first VSA product X13-VSA PRO Cobra (including a unique high-quality IVSA process) which is used today by the Italian State Police and the International Crime Analysis Association.
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: The primary suppliers worldwide are: NITV(USA)-CVSA; POLYVSA(TVT Centre RSA)- AVSA PRO 1_7KT & 2_0AG, Truth & Deception Technologies -DecepTech; Expertos and PSE 5128. ( Deceptech markets software previously known as Lantern Professional.)
The primary use of VSA is in the arena of "Detection Of Deception". As with the polygraph, manual VSA technology is inert and has no artificial intelligence component. However, the advent of AVSA PRO introduced Artificial Intelligence into the DOD arena. AVSA PRO utilises a neural network ( a training database) that relies on the input of VSA expert scoring. AVSA PRO eliminates common examiner errors and incorporates inviolate timing delays to enforce homeostasis and to make provision for the Onset Delay of the FOF syndrome.
The use of the recorded data as a means for lie detection that remains controversial. However, there are well-document cases where confessions were obtained after DoD devices indicated stress that led to confessions by suspects that were later definitively proven innocent. In civil court testimony, the CVSA founder testified that "NITV acknowledges that the CVSA is not capable of lie detection and specifically cautions its users regarding proper use of the device."
The purpose of a VSA examination is to attempt to determine the truthfulness of responses made by an examinee regarding the subject under investigation. Determinations are made by analyzing and scoring the degree of voice stress on 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 voice stress may indicate that the examinee is deceptive as is the case with polygraph, though the polygraph uses multiple modalities. In respect of VSA, squared voice grams indicates less frequency in the uttered response; repetitive patterns presenting and thus higher stress whilst 'wave form' or 'domed' signatures indicate less stress. Manual scoring of old (obsolete) VSA systems is extremely difficult and often unreliable.
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'.
Professional VSA instruction follows the polygraph model of PDD training and uses Backster and Reid question protocols. Any deviation from scientifically validated protocols renders the process to be unreliable. Question protocols containing >12 questions and multiple issues are invalid and unreliable.
It is of utmost importance that a VSA Instructor should have received APA grade PDD training AND Instructor certification from at least One polygraph manufacturer. Basic PDD training should be strictly observed and administered. Low standards of training produce poor examiners.
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 covertly, since all that is needed is a voice, a microphone or a tape recording.
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, some 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. The biggest user of VSA technology in the USA is US law Enforcement agencies, despite the lack of any scientific studies that demonstrate any degree of accuracy greater than chance. Law Enforcement agencies in Israel, India, Malaysia, South Africa, China, Hong Kong, Poland, Russia, use VSA alongside polygraph.
Methodology and accuracy 
The McQuiston-Ford algorithm used for Voice Stress Analysis is reliably accurate. and Funded by the National Institute of Justice, a three-year study by the AFRL determined that voice stress analysis achieved an accuracy rate of 100% when used to detect stress in 45 known-conclusion responses.
(Available from http://anype.com/SURF/http://extraafrl.af.mil/news/fa1100/features/detects:stress:feature.pdf).</ref>[verification needed] The recorded "micro tremors" in a person's 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.
Polygraph-only associations have disputed the accuracy of VSA although many accredited polygraphists have trained in the use of VSA. The traditional analysis and scoring of voice-grams by means of assigning 'percentages' is time consuming, has been replaced by 7 position scoring and lately by AVSA PRO auto scoring.
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. and
The American Polygraph Association's website lists conclusions from multiple studies, 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.[verification needed]
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://anype.com/SURF/http://www.nap.edu/openbook.php?isbn=0309084369 )
Notable examples of use 
In the 2012 case of George Zimmerman shooting to death Florida teenager Trayvon Martin, Zimmerman was given a voice stress analysis test by the police department of Sanford, Florida following the shooting, which he passed it. A videotape of the test was publicly released in June 2012.
- Ruiz, Selye, & Guell, 1990. Voice analysis to predict the psychological or physical state of a speaker. Published in Aviation, Space, and Environmental Medicine, 1990. Ruiz et al. reports that their “research suggests that psychological stress may be detected as acoustic modifications in the fundamental frequency of a speakers voice” and “that the fundamental frequency of the vocal signal is slowly modulated (8-14 Hz) during speech in an emotionally neutral situation. In situations demanding increased ‘mental or psychomotor’ activity, the 8-14 Hz modulation then decreases as the striated muscles surrounding the vocal cords contract in response to the arousal, thus limiting the natural trembling”
- Mitchell S. Sommers, an associate professor of psychology in Arts & Sciences at Washington University in St. Louis's Results. 
- Horvath, F. "Detecting deception: the promise and the reality of voice stress analysis." Journal of Forensic Science. 1982 Apr;27(2):340-51. PMID 7047675
- As documented by Olof Lippold – The Lippold Tremor.
- Refer NAS 2003 in reference to all APA related research projects.
- Haddad et al
- Diogenes & CVSA
- Haddad, Walters Study 2002, doc 193832
- Charlatanry in forensic speech science: A problem to be taken seriously Anders Eriksson and Francisco Lacerda IJSLL (print) issn 1748-8885 IJSLL (online) issn 1748-8893 http://www.cs.columbia.edu/~julia/papers/eriksson&lacerda07.pdf
- "Lie Detector Company Threatens Critical Scientists With Suit". Slashdot. 2009-01-29. Retrieved 2009-02-02.
- The Diogenes Company. Retrieved 9 February 2009.
- Chapman, J. Criminal Justice Department, Corning Community College, NY. "The Psychological Stress Evaluator As A Tool For Eliciting Confessions", 1989. Chapman selected 211 criminal cases at random from 2,109 known-conclusion cases where voice stress analysis was used to test suspects. Professor Chapman’s study confirmed that voice stress analysis was accurate when utilized as a truth verification device and produced a confession rate of 94.8% of the cases where deception was indicated
- Heisse, J. “Is The Micro-Tremor Usable? - The Micro-Muscle Tremor In The Voice.” U.S. House Subcommittee of the Committee on Government Operations, 1974. Heisse analyzed 91 known-conclusion criminal cases utilizing voice stress analysis and determined that “Audio stress analysis seems to be valid in detecting changes in various psycho physiological parameters so that a trained examiner utilizing standardized techniques can evaluate these changes and thus utilize the instrument in truth and deception”.
- Honts 1993
- Honts, C. R., and Hodes, R. L., “The Effect of Simple Physical Countermeasures on the Detection of Deception," paper presented at meetings of the Society for Psychophysiological Research, Minneapolis, Minn., 1982.
- Honts, C. R., and Hodes, R. L., “The Effects of Multiple Physical Countermeasures on the Detection of Deception," Psychophysiology 19:564-565 (abstract), 1982.
- Honts, C. R., and Hodes, R. L., “The Effect of Simple Physical Countermeasures on the Detection of Deception," Psychophysiology 19:564 (abstract), 1982.
- Honts, C. R., Raskin, D. C., and Kircher, J. C., “Detection of Deception: Effectiveness of Physical Countermeasures Under High Motivation Conditions, " 1 paper presented at meetings of the Society for Psychophysiological Research, September 1983.
- "Over 1700 Agencies Utilizing the CVSA".
- see W.Carolina Uni paper 140 , Eng 101 , 2008 Tay,Adams,etc
- Air Force Research Laboratory, Rome, NY, October, 2000
- Chapman, J. Criminal Justice Department, Corning Community College, NY. “The Psychological Stress Evaluator As A Tool For Eliciting Confessions”, 1989. Chapman selected 211 criminal responses at random from 2,109 known-conclusion responses where voice stress analysis was used to test suspects. Professor Chapman’s study confirmed that voice stress analysis was accurate when utilized as a truth verification device and produced a confession rate of 94.8% of the responses where deception was indicated.
- APA Website
- membership list on SAPAVSA.co.za details many dually trained examiners
- Truth Extraction ISBN 0-86486-464-7
- Lippold, O. “Oscillations In The Stretch Reflex Arc And The Origin Of The Rhythmical 8-12 C/S Component Of The Physiological Tremor.” The Journal Of Physiology, February, 1970. Lippold first discovers the physiological tremor in the human voice in the 8-12 Hz range (Available from Library of Congress)
- Lippold, O., Redfearn, J., Vuco, R. “The Rhythmical Activity Of Groups Of Muscle Units In The Voluntary Contraction Of Muscle.” The Journal Of Physiology, August, 1957. Lippold, Redfearn and Vuco begin exploring the correlation between muscle activity and stress (Available from Library of Congress).
- Cestaro, V. Department of Defense Polygraph Institute, Ft. McClellan, AL. “A Comparison Between Decision Accuracy Rates Obtained Using the Polygraph Instrument and the Computer Voice Stress Analyzer in the Absence of Jeopardy”, August, 1995. Cestaro reports that “the lab simulations established that the CVSA performs electrically according to the manufacturer’s theory of operation” and, even in the absence of jeopardy, which is a basic requirement in detection of deception, “These data indicate that there may be a systematic and predictable relationship between voice patterns and stress related to deception” (Available from DoD web site: http://anype.com/SURF/http://www.dodpi.army.mil/research/research.htm)
- Kovaleski, Serge F. (May 16, 2012). "Trayvon Martin Case Shadowed by Series of Police Missteps". NY Times. Retrieved May 22, 2012.
- Stutzman, Rene (June 21, 2012). "Tape released of Zimmerman’s re-enactment of Martin shooting". Orlando Sentinel.