On Thu, 2005-11-10 at 12:49 +1300, Matt Riddell wrote:
> > The frequencies are generally between 8-14Hz.  While these frequencies
> > by themselves generally cannot pass a telephone network (300-3300Hz US
> > 300-3400Hz EU typically) when mixed with other frequencies they can be
> > passed.  This is the same principle that china used for its C5 links
> > with america, a 2600+2400+60Hz tone followed by 2400Hz would seize the
> > line there (at least a few years ago, I dunno about now, or even if they
> > are still C5r1).  60Hz by itself cant go but it modifies the waveform of
> > the other tones and can be pulled out.
> 
> Wouldn't you also need a base recording of someone not lying?  Otherwise
> wouldn't you end up saying people with deep voices lie?
> 
This pitch shift goes up when stress is present (muscles flexing more).
So it would kinda be the other way around, but its mostly inaudible to
humans.  If you have the whole call, you would look for deviations, a
baseline is required per person, it would be better if you could key it
ahead of time, but basically you would want to show where in that range
the majority of the energy is, so that you can try to guage as the call
progresses.  A numeric value would be better than a yes/no ... 

Its mostly a toy, but a fun toy I think anyway, unless its your
girlfeiend that is using it :P

-- 
Trixter http://www.0xdecafbad.com     Bret McDanel
UK +44 870 340 4605   Germany +49 801 777 555 3402
US +1 360 207 0479 or +1 516 687 5200
FreeWorldDialup: 635378

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