cvsa

[False +]

Rescue_Ranger,

I recently had occasion to observe a CVSA operator conduct an examination and I was able to view the screen of the CVSA laptop.

After each answer given, a graph appeared that bore many similar features to a frequency-domain representation of a voice signal. Is it simply an FFT (or FFT plus some added filtering) of the voice signal? I ask because you made reference to an HP Spectrum Analyzer in your post, so I assume you must have some signal analysis background (as do I).

If the backbone of CVSA is indeed the FFT, the CVSA industry is even more back-handed that the polygraph industry. It would then mean that a truthful "yes" or "no" is assumed to appear more sinusoidal, like a "pure tone", and not have any additional frequency components. There's absolutely no reason at all to believe that a truthful response couldn't have these additional components. WHAT A SHAM ALL THIS IS!!!!

[Darrel]

I am the founder of a small, vocal, Freethinker/skeptical group here in the South and our local police station (city population 55,000), have purchased one or more of these CVSA programs. From what I have seen so far it appears to be  nonsense. I am researching an article for our local paper and for a lecture I am giving this weekend. I hope to interview the police about the device, perhaps tomorrow. I need some really good, the best, info roasting this stuff so I can do a good job of drawing attention to this waste of money.
   I emailed the "National Center for Truth Verification" who I think they bought them from ($10,000 a pop plus $1,600 per person per week for training). I asked them for any scientific, peer-reviewed evidence that their devices work, and asked them what they claim for accuracy. They have not responded. Our city is having a bit of a budget crisis and I am a little pissed that all this money has been spent on this nonsense.
   Any help is appreciated. Thanks, Darrel

ph. 479-442-6738

[Darrel]

My email is dardedar@aol.com

[George W. Maschke]

The CVSA is an overpriced prop for interrogations. To my knowledge, there is no peer-reviewed research available regarding CVSA, and the only studies purporting to support its validity as a lie detector come from the manufacturer.

The best source I could refer you to is David T. Lykken's book, A Tremor in the Blood: Uses and Abuses of the Lie Detector (2nd ed., 1998). Chapter 11 deals with voice stress analysis.

On the Internet, you'll find details of some studies conducted by the Department of Defense Polygraph Institute on the following website:

http://www.voicestress.com

It's amusing that the operator of the above site promotes the competing pseudoscience of polygraphy.

I'd be interested to hear how your presentation goes!

[Rescue_Ranger]

F+, you're correct.  Whether they're using FFT, IFT or DFT, the bottom line is it's pretty easy to look at and for additional 'stress' components.  I also think they're susceptible to high Signal to Noise, another interesting alternative.

Question to future CVSA subjects:  Would you pay $40 for small device that lets you control the output of a CVSA?
(need ~ 100 interested parties, or lower price for more units)
RR

Posted by: False +
  
              I recently had occasion to observe a CVSA operator conduct an examination and I was able to view the screen of the CVSA laptop.

[antant00]

yep pay $ 40.00 bucks just for the fun of it....and would hope it works...lol