Is this really a real effect or is it a special effect of some kind?
http://youtube.com/watch?v=XjCmwuGKR6g
I don't believe the voices!

Wasn't it who wrote:
>Is this really a real effect or is it a special effect of some kind?
>http://youtube.com/watch?v=XjCmwuGKR6g
>I don't believe the voices!

It seems real.

Wikipedia believes it

http://en.wikipedia.org/wiki/Sulfur_hexafluoride

'Due to its high density, sulfur hexafluoride is often used in public
"magic" tricks where it is renowned for being "invisible water".'

--
Mike Williams
Gentleman of Leisure

Mike Williams skreiv:
> Wasn't it who wrote:
>> Is this really a real effect or is it a special effect of some kind?
>> http://youtube.com/watch?v=XjCmwuGKR6g
>> I don't believe the voices!
>
> It seems real.
>
> Wikipedia believes it
>
> http://en.wikipedia.org/wiki/Sulfur_hexafluoride
>
> 'Due to its high density, sulfur hexafluoride is often used in public
> "magic" tricks where it is renowned for being "invisible water".'

Not only is it real, but it's kinda obvious too.

There's nothing special about sulfur hexafluoride other than being
nontoxic and fairly heavy. Any other gas having those two
characteristics would work just as well, such as Xenon. (that's more
expensive though)


Eivind

On Feb 17, 9:13 pm, jmcphee...@gmail.com wrote:
> Is this really a real effect or is it a special effect of some kind?http://youtube.com/watch?v=XjCmwuGKR6g
> I don't believe the voices!

The scientific explanation:

In air (a mixture of oxygen, nitrogen, and carbon dioxide, as well as
other trace elements) sound has a medium rate of travel. (i.e. The
sound waves travel at about 340 m/s at sea level.) Because of this
medium rate of travel voices (which are created by vibrating your
vocal cords in your throat) sound normal. The vibrations travel
through the air at their normal speed. when you inhale helium and then
speak the sound of your voice gets higher because the sound of your
vibrating vocal cords travels faster in helium than in air. With
sulfur hexafluoride it's the opposite, the sound of your vibrating
vocal cords travels slower making the sound deeper. As has been
mentioned elsewhere, there is nothing special about sulfur
hexafluoride that other heavy gasses can't do, except that it won't
kill you if you inhale it. (As long as you make sure you get some
oxygen into your system often enough that you don't pass out.)

On 19 veebr, 16:00, CharlesRCap...@gmail.com wrote:
> On Feb 17, 9:13 pm, jmcphee...@gmail.com wrote:
>
> > Is this really a real effect or is it a special effect of some kind?http://youtube.com/watch?v=XjCmwuGKR6g
> > I don't believe the voices!
>
> The scientific explanation:
>
> In air (a mixture of oxygen, nitrogen, and carbon dioxide, as well as
> other trace elements) sound has a medium rate of travel. (i.e. The
> sound waves travel at about 340 m/s at sea level.) Because of this
> medium rate of travel voices (which are created by vibrating your
> vocal cords in your throat) sound normal. The vibrations travel
> through the air at their normal speed. when you inhale helium and then
> speak the sound of your voice gets higher because the sound of your
> vibrating vocal cords travels faster in helium than in air. With
> sulfur hexafluoride it's the opposite, the sound of your vibrating
> vocal cords travels slower making the sound deeper. As has been
> mentioned elsewhere, there is nothing special about sulfur
> hexafluoride that other heavy gasses can't do, except that it won't
> kill you if you inhale it. (As long as you make sure you get some
> oxygen into your system often enough that you don't pass out.)


Or continuously. Just mix the sulphur hexafluoride with adequate
amount of of oxygen beforehand.

But sulphur hexafluoride is narcotic. More so than argon and even
krypton.

CharlesRCaplan@gmail.com wrote:

> ... The vibrations travel
>through the air at their normal speed. when you inhale helium and then
>speak the sound of your voice gets higher because the sound of your
>vibrating vocal cords travels faster in helium than in air. With
>sulfur hexafluoride it's the opposite, the sound of your vibrating
>vocal cords travels slower making the sound deeper. ...

The speed of sound through the gas might well be different but it won't
shift the frequency.

I'm not sure, but I presume that the density of the medium actually
alters the frequency at which the larynx vibrates. Or it might have
something to do with the way that the overtones are filtered.

--
Dave Farrance

In article <dldmr3t5o175gdpo69eathnlp0v3tk1dc0@4ax.com>,
Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> wrote:

> CharlesRCaplan@gmail.com wrote:
>
> > ... The vibrations travel
> >through the air at their normal speed. when you inhale helium and then
> >speak the sound of your voice gets higher because the sound of your
> >vibrating vocal cords travels faster in helium than in air. With
> >sulfur hexafluoride it's the opposite, the sound of your vibrating
> >vocal cords travels slower making the sound deeper. ...
>
> The speed of sound through the gas might well be different but it won't
> shift the frequency.

The frequency *is* dependent on the speed of sound in the gas. Increased
density at 1atm pressure corresponds to decreased speed of sound.

> I'm not sure, but I presume that the density of the medium actually
> alters the frequency at which the larynx vibrates. Or it might have
> something to do with the way that the overtones are filtered.

Don't forget that the larynx is just part of a resonant system along
with the trachea, mouth and sinus cavities; all of which will be
affected by the speed of sound of the gas that fills them.

In article <400c4261-fd74-4f95-bbaa-945a108b05d5@i12g2000prf.googlegroups.com>,
<jmcphee888@gmail.com> wrote:
>Is this really a real effect or is it a special effect of some kind?
>http://youtube.com/watch?v=XjCmwuGKR6g
>I don't believe the voices!

The "Mad Scientist Guy" that Jay Leno has on every now and then did
the "breathing sulfur hexafluoride" trick once. After he did it, he
hung upside down and breathed deeply for a few seconds to get it out
of his lungs; he said that otherwise, much of it would stay there.

(I'm not sure how much I believe that; even though it's a very heavy
molecule, there's still some mixing.)

His voice on SF6 did have the same muffled/distorted quality as
the girls' voices.

--
Mike Van Pelt | Wikipedia. The roulette wheel of knowledge.
mvp at calweb.com | --Blair P. Houghton
KE6BVH

Mike Van Pelt skreiv:

> The "Mad Scientist Guy" that Jay Leno has on every now and then did
> the "breathing sulfur hexafluoride" trick once. After he did it, he
> hung upside down and breathed deeply for a few seconds to get it out
> of his lungs; he said that otherwise, much of it would stay there.
>
> (I'm not sure how much I believe that; even though it's a very heavy
> molecule, there's still some mixing.)

There is more than "some" mixing, the lungs are infact very good at
thouroughly mixing gases with different densities. At the speed and
turbulence-level present in the lungs, the gases will be near perfectly
mixed, even with -normal- breathing. (nevermind vigorous breathing)

I doubt you could find -any- detectable difference in sulfur
hexafluoride-concentration in the lungs after taking 10 normal breaths
standing up versus taking 10 normal breaths while hanging upside down.

The "must stand on your head" thing is a urban myth.


Eivind Kjorstad

In article <fpjvgl$rj6$2@news.netpower.no>,
Eivind Kjorstad <eivindorama@gmail.com> wrote:
>I doubt you could find -any- detectable difference in
>sulfur hexafluoride-concentration in the lungs after taking
>10 normal breaths standing up versus taking 10 normal
>breaths while hanging upside down.
>
>The "must stand on your head" thing is a urban myth.

This doesn't surprise me a bit.

I'm not sure why David Willey did the "hang upside down" bit,
but he did. Maybe just for laughs.

--
Mike Van Pelt | Wikipedia. The roulette wheel of knowledge.
mvp at calweb.com | --Blair P. Houghton
KE6BVH