Voice Stress Analysis (VSA) is a validated PDD system. It has been subjected to many research projects since 1970. It is as reliable as BFP when used by properly trained and accredited examiners. One recent study validating VSA is the Patil et. al. research paper.
Link: View full paper .
VSA vs LVA – Layered Voice Analysis
LVA is not VSA. Mainstream VSA utilises the science of spectrography and the Lippold Tremor in voice as it’s underpinnings. The Lippold tremor is a scientifically validated phenomenon discovered by Dr Olaf Lippold in circa 1955. Lippold Tremor based VSA is the only VSA delivering reliable and proven results on par with Biofeedback polygraph.
LVA technology makes decisions based on variances in pitch and tone of voice. This is unreliable as humans can hear the pitch and tone (highness/lowness of : intonation, timbre, modulation of expression) in their voices and knowingly alter pitch and tone for effect. Altering ones’s pitch and tone has a profound effect on LVA results.
VSA – The Lippold tremor is a subsonic quality. You cannot hear it, therefore you cannot affect it. When a person lies to avoid consequences, he/she experiences the Flight Or Fight condition. The FOF condition causes involuntary muscles to tense, in addition to other physical behaviours.
There are sixteen laryngeal muscles, six of which are directly control vocal production. https://en.wikipedia.org/wiki/Larynx When these muscles tense, there are measurable variances in the voice microtremors. The behaviour of the microtremors can only be viewed and analysed with sophisticated software. There are only few VSA programs that can identify and display the microtremor.
Validated VSA Systems
Of the manual VSA systems, the most advanced and reliable system is Diogenes. (no longer available) CVSA from NITV is a reliable manual system. PSE from Dektor is the original, but is archaic in operation and time consuming to work with. Diogenes evolved into AVSA, a semi automated VSA system. AVSA evolved into AVSAPRO under the development of Clifton Coetzee, an internationally renowned VSA developer. Avsapro utilises neural network processing. Voice graphics may be scored manually or automatically.
To see Screenshots click on this link > http://avsapro.com/screenshots/.