Voice Stress Analysis

VoiceStress Analysis

VoiceStress Analysis


Thispaper compares two articles, “PsychologicalStress Evaluator: The Theory, Validity and Legal Status of anInnovative Lie Detector,”which concerns a polygraph examination, and “Voicestress analysis: Only 15 percent of lies about drug use detected infield test,”addressing voice stress analysis (VSA).

Theparties involved in law enforcement are provided with technologicalequipment that will make carrying out their work easier. Due to theadvancement of technology law enforcers need to have the latesttechnologies and be conversant with them when conducting theirvarious duties. However, technology is very expensive, and not allagencies can afford the luxury of having technological gears due totheir high initial buying cost as well as the additional costs oftraining, operating and maintaining the equipment alongside thepersonnel. The military has embraced technology with the use ofspeech recognition technology, and this has significantly beenadvanced as voice stress analysis it has been employed inquestioning to get intelligence. Voice stress analysis (VSA) has beenseen to be superior to polygraph examinations because the latter canonly test 2 people in a day while the former can test 6 people daily(Damphousse,2011).As such, law enforcement agencies consider the VSA as attractive incomparison to polygraphs (Pavlidis,Eberhardt, &amp Levine, 2012).The polygraph has its downside in that it is not sufficiently andconclusively reliable and accurate and for that reason, its tests arenot admissible in a court of law.

Severalresearchers claim that the voice stress analysis sometimes makessuspects make confessions, and in some instances, they can evenincriminate those who are innocent. In court, the Computer VoiceStress Analyzer (CVSA) is not admissible under a similar statutewhich the polygraph is inadmissible. In 1970, the VSA emerged, andthe research conducted stipulated that the polygraph is moreefficient in detecting lies, as compared to the VSA. An example wasgiven whereby in 1999 there was a civil rights suit which was theofficer of the county public affairs in San Diego because the VSA wasused to create fake confessions regarding murder by the adolescentpeople (Damphousse,2011).

Inessence, the notion that 98% of the confessions are right is based onthe satisfied customers, rather than on independent research. Thus,the reliability and preciseness rest on the company and anyinvestigation conducted. On the other hand, in polygraph tests, theones who are involved are the professional polygraph testers and thepeople being tested. Despite the fact that there exists evidence thatpolygraph testing is useful, a rate of error was found in theevidence as well. There exist no studies to reveal information whichis not disclosed from the screened government workers.


Thelimitation of using the polygraph is that it cannot be used solely toconvict a person. There must be overwhelming evidence against theindividual being supposedly at fault, and the polygraph comes intoplay here so as to conclude what one already knows. The polygraphcannot be used in place of evidence because it is unreliable andusing it as the only thing to incarcerate someone would be unfair. Itwould be like comparing it to the Salem Witch Trials which foundpeople guilty only because of accusations and the victims ended upsuffering or dying because of that. There are different accuracyrates and variances from state to state which is most attributed tohuman error that comes with using the polygraph for questioning(Pavlidis,Eberhardt, &amp Levine, 2012).There are problems that polygraph administers face when using thisdevice on individuals with underlying psychological or anxiety issuesas it cannot work properly on these people. The polygraph examinationtends to measure an individual`s heart rate, pulse and blood pressurein the event a person is afraid of being punished or persecuted thepolygraph will see the individual as being under stress and thereadability of the examination will not be conclusive.

Theinvestigator may be subjected to moral and legal implications if theyuse techniques, which are not validated for disciplining employees orscreening applicants, regarding the VSA. The only aspect separatingthe CVSA from the polygraph is paper, versus the computer screen`sdisplay. There exist no analytical techniques or scoring systems forelucidating the CVSA`s results. Despite the fact that the CVSAdetects the offenders` high stressed voice, science is not present toprove it(Pavlidis, Eberhardt &amp Levine, 2012).Another challenge is that the government does not have anyregulations regarding the devices since the departments and statesare warranted to make their personal rules. Several critics claimthat the CVSA is not scientific, is biased, and is financed by theindustry.

Inboth VSA and polygraph testing, there is an absence of any scientificbasis to evaluate these devices. For all findings, there is noscientific basis research as well. Therefore, the critics may beright when they claim that the industry is financed so as to bebiased. People have to have a fair trial, thus solely using eitherof the devices would be unfair, as the results would be inaccurate.Additionally, for an individual to be convicted there has to beenough evidence from other places, which show that the crime wascommitted without reasonable doubt.


Liedetection has not found its way in the court of law over the past fewcenturies since it was not developed in the 21st century it has longbeen in existence. Deception has been on for centuries and methods todetect this have been formulated to find out those telling the truthfrom those lying (Kenety, 2013). There have been scientificinnovations and inventions used for lie detection due to theadvancement of technology.

Liedetection evidence was first acknowledged in the United States versusFryer case in 1923. Lie detection evidence technology was excluded inthe courts as it lacked sufficient acceptable scientific evidence.The exclusion of the technology of lie detection evidence came to befamously known as the Fryer standard, and in most states, in theUnited States, it has being used as the norm. In the Scheffer versusthe United States, the Supreme Court dealt with the use of polygraphadministration on an individual standing trial and ultimately bannedits use in 1997.

Thecourt decided that the per se ban on the proof of a polygraph doesnot contravene the right of the defendant to a fair defense under thesixth amendment. Unsuitable employment of dicta from Justice Thomas’view regarding Scheffer has become typical for courts which look touphold the lie detection’s exclusion in several jurisdictions. Theprobability of a systematic bias is not addressed in Scheffer’scase. Notably, there is no other kind of evidence which has beenhighly scrutinized and excluded on legal grounds which areunjustifiable. However, some jurisdictions accept the polygraph,whereby only 29 states block any proof from the polygraphs. In mostjurisdictions, the problem emanates from the issue of reliability,accurateness, and validity, because scientific standards which wouldbe used to evaluate the polygraph are inexistent (Kenety, 2013).


Damphousse,K. R. (2011). Voice stress analysis: Only 15 percent of lies aboutdrug use detected in field test.&nbspNIJJournal,&nbsp259,8-12.

Kenety,W. H. (2013). Psychological Stress Evaluator: The Theory, Validityand Legal Status of an Innovative Lie Detector, The. Ind. LJ, 55,349.

Pavlidis,I., Eberhardt, N. L., &amp Levine, J. A. (2012). Human behaviour:Seeing through the face of deception.&nbspNature,&nbsp415(6867),35-35.