Voice Stress Analysis

We do Voice Stress Analysis with AVSA PRO

Voice Stress Analysis is the modern method for Lie Detecting!


Voice Stress Analysis
Recording of the voice is the only data capturing done during a Voice Stress Examination

Voice Stress Analysis, being the most modern method of Lie Detecting has over the past years become the preferred service to unlock the truth in the Detection of Deception.

  • VSA – is accurate when the best software available globally, is used.
  • Voice Stress Analysis is reliable – Using correct protocols to best fit the situation under investigation is especially relevant.
  • Voice Stress is affordable – in these tough economic times there is never a ‘good’ time to need the services of a Voice Stress Examiner. Our Network offers the best value for money, and represents the most time efficient Lie Detecting method.


Single incident – The Integrated Zone of Comparison Technique (IZCT)  is used for single incident issues.

Screenings are regular, single recording examinations containing several Relevant Questions and two Control Questions. Subjects are tested regularly for deviant behavior in their employment environment. The regularity of such examinations can subsequently be bi-annual or even as regular as quarterly.

Pre-employment Screenings – These single recording examinations containing several Relevant Questions and two Control Questions should include topics such as substance use, verifiable qualifications, theft, involvement in crime, etc.


Some Voice Stress Analysis software use a theory introduced by the British physiologist Olaf Lippold, 1957. They extract the low frequency of about 8 to 12 Hz and deduce a value of stress.

BUT, AVSA PRO uses a new technique for calculating the value of stress, not based on a direct calculation of the micro-tremor but rather uses a knowledge base collected from several Voice Stress Analysis experts. Thousands of samples were processed, and approximately 1 200 retained.

When a totally independent scoring exercise was conducted by VSA experts, at the culmination of the project it was notable that 80% of the results had only 5% difference on the estimated values of stress, which provide a consistent and reliable basis for the techniques used by AVSA PRO.

There is also no need to formalize mathematically complicated formulas to extract frequencies of micro-tremors, as the neural processor teaches itself how to deduct the outcome on the basis of data provided.


It is totally free from the assumption of 8Hz indicating low stress and 12 HZ indicating the presence of stress. The certainty lies in the know-how of human experts who have conducted thousands of successful Voice Stress Analysis examinations, together with known solution outcomes.

AVSA PRO can calculate up to 20 estimates of stress per second on a standard PC. Chart tests (validated protocols) are scored within 2 seconds. Exam scores (average of the tests conducted) are displayed instantly at the culmination of the last test chart.

All examiners of this Network consequently make use of some version of AVSA.

If it is not AVSA PRO it is obsolete!

All examiners are members of applicable associations that require full adherence to universally accepted detection of deception protocols.

Why shop around taking unnecessary risks if you can go directly to the industry leaders?

For immediate assistance give us a call on 082 72 72 153, email, or alternatively, complete the Inquiry Form, and our team will be in contact within 24 hours.

Frequently Asked Questions

Q. What is VSA?
A. It is a Psychological Stress Evaluator which measures the subsonic reactive elements of the voice which cannot be stopped. These reactions form part of the autonomous nervous system, like breathing, heartbeat, etc, which in turn is regulated between the Sympathetic and Parasympathetic Systems.

Q. What is the Sympathetic System?
A. Flight or Fight activation system within the subject’s body and psychological setup. Easiest detected signs are that the subject’s eyes will dilate (become wider open) and breathing will change. The heart also pumps more blood to the major muscle groups (torso).

Q. What is the Para-sympathetic System?
A. The body’s normal, relaxed state. Breathing is deep and slow, blood flow is even throughout the body, and the smooth muscles around the larynx measure between 8 – 14Hz.

Q. How accurate is VSA?
A. Extremely accurate when the consequences are relevant – How much and what does the subject have to lose if caught lying.