[Asterisk-Users] Realtime Voice Changer Patch

[Matt Riddell]

trixter aka Bret McDanel wrote:

> I will give you one of my super secret someday projects.  A voice stress
> analyzer built into asterisk (would be done in a similar way in terms of
> interfacing, perhaps just play a beep or if non voice only circuit send
> text).

:) Nice!

> VSAs work by detecting subharmonics present when a person is under
> stress.  Basically when stressed there are slight increases in muscle
> tension that pull on vocal cords this causes a specific set of
> sunharmonics to shift upwards slightly.  Applying a dsp filter to that
> and detecting those changes will result in a stress indicator. 

The key is changes.  Changes to base - i.e. can't start call by lying :)

> Most people are conditioned to believe lying is wrong (whether or not it
> is I wont comment here).  As a result they exhibit stress when they lie.
> This is how a polygraph works, by measuring physical responses to what a
> subject thinks is wrong.

Kewl.

> While this is not that accurate, you dont know what is causing the
> stress, you can see when it presents itself in relation to what is
> spoken and try to make some guesses.

Yep.

> 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?

> Now you have an all new super secret someday project so your list doesnt
> get shorter ! :)

HEHE!!! You da man!

-- 
Cheers,

Matt Riddell
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