Voice Stress Analysis

Voice Stress Analysis (VSA) is a lie detection technology- and uniquely deployed as such- which is newer than the polygraph, but still controversial.[1]
VSA technology records 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'.[2]
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 lies 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 by polygraph-industry initiated research. 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.[3][4]
For example, a 2005 study found the TrusterPro LVA system to be invalid for detection of guilty knowledge. Research commissioned by the Department of Justice and conducted by AFRL (Air Force Rome Labs), as well as several other researchers, also suggested less accuracy rates for the same system, marketed in the US under a different name ("Vericator").
The skill and experience of the VSA Examiner is of utmost importance.[5]
LVA - Layered Voice Analysis technology- known as LVA or VRA - is finding use as a screening tool in the UK, in which recipients of jobless benefits are faced with the 'threat only' of a test, and would consequently face more scrutiny if they "failed".
The LVA test itself has accuracy levels less than chance (50%) but the mere threat is used in this instance. [6]
LVA trials conducted by private Polygraph & VSA Instructor/Examiners in South Africa produced reliability levels of  <30 a="" and="" association="" consequently="" for="" href="http://en.wikipedia.org/wiki/Voice_stress_analysis#cite_note-6#cite_note-6" is="" lva="" membership="" non="" of="" polygraph="" qualifying="" sa.="" stress="" technology="" the="" title="" to="" voice="">[7]
, the consumer version of the LVA technology, is available in different products and produces non-useful readings such as 'love' and 'Embarrassment' (not relevant in DOD applications).[8]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. [9]. http://www.polyvsa.co.za  http://www.avsapro.com