Re: Liquid breathing
- From: "Stuart" <stuart€@whodunnit8.com>
- Date: Tue, 14 Aug 2007 05:36:46 GMT
"John Schilling" <schillin@xxxxxxxxxxxxx> wrote in message
news:oh13c39ig70f1h59s9labpr5u7u3kofjhe@xxxxxxxxxx
On Fri, 10 Aug 2007 22:56:35 GMT, "Stuart" <stuart?@whodunnit8.com> wrote:
"John Schilling" <schillin@xxxxxxxxxxxxx> wrote in message
news:3s4pb35rql3rrdge23qiandslc69imlnlk@xxxxxxxxxx
On Fri, 10 Aug 2007 04:06:19 GMT, "Stuart" <stuart?@whodunnit8.com>
wrote:
I'm writing a science fiction novel, which will involve a man whose
body has been reshaped for breathing underwater. I'm researching what,
if any, changes will have to have been made to his vocal chords, in
order for him to be able to talk with his lungs and trachea filled
with sea water.
In the film, The Abyss, the man liquid breathing with perfluorocarbon
was unable to speak, but perfluorocarbons are much denser (around
twice?) than water, let alone air. Would 'beefed up' vocal chords
allow him to speak in water? Would they still function in air, and if
so, would his voice be deeper or different in any other way?
Thanks very much. :-)
Charl
The pitch is lower - get hold of an underwater speaker and a hydrophone
and check it for yourself.
How do you imagine any of us could try this ourselves without drowning?
Keep in mind, the issue is *NOT* what would happen if someone were to
speak while breathing air, with a larynx full of air, and then tranfer
the acoustic signal to water.
Sorry for not being clearer - I did this as part of a low budget TV film
( I
used to be a sound recordist before retiring) and what we did was
pre-record
the actors voice, played it back via a high quality hydrophone and
positioned a microphone secured in a condom about 2 metres from the
hydrophone and recorded the effect. ( we were around 2 metres down ) Now
the
mathematics of it would suggest the pitch would go up as in the use of
helium but the resulting effect actually was perceived as slightly lower
with a lot of phasing effects due to the scattering effect that takes
place
under water. This was done off the coast of Cairns (Australia) way back in
the early '70's.
Sounds like fun, but it still doesn't address the right issue. And just
what mathematics ever lead you to suspect the pitch would go up? Once
the sound is generated, in this case by recording an actor's normal voice
in air, it's not going to change. Doesn't matter whether you replay it
in helium, water, molasses, or molten lead, the pitch is going to stay
the same.
A middle C, for example, is a series of pressure waves sequenced 3.822
milliseconds apart. Whatever path they take to whatever reciever you
may set up, so long as the path remains constant the pressure waves
are going to arrive 3.822 milliseconds apart and the reciever is going
to hear middle C. Speed the waves up, slow them down, amplfy them,
attenuate them, record them and play them back a fixed time later,
sheck, send them through a wormhole, o long as you do it consistently
you're always going to have the same frequency you generated in the
first place.
As you note, a complex sound involving multiple frequency components may
be slightly distorted by differential attenuation, but that still doesn't
change the actual frequency of any of the components.
The bit where someone breathing helium speaks with a high-pitched voice,
is because the sound is generated at that high pitch in the first place,
in a larynx full of helium with its resonant properties thus altered.
And again, what happens *afterwards*, what medium you transmit the sound
through, doesn't change the frequency. Record the voice of someone
speaking in helium, then play it back under water (or molasses, molten
lead, or whatever), and you'll get the same squeaky voice.
What people here have been asking is, what happens if someone tries to
speak when their larynx is full of water? This is *not* the same thing
as what happens when someone speaks with a larynx full of air and the
sound is subsequently transmitted through water.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
*schillin@xxxxxxxxxxxxx * for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *
Yes I completely missed that important point - apart from probably drowning
trying to speak with a larynx full of water my guess is the only way to find
out would be to construct an artificial underwater larynx, modelled on the
human larynx and modulate it with a instruction set of data (not audio) a
bit like midi; a midi music file doesn't actually contain any audio just
data to trigger whatever soundcard you have to synthesize the sound so a
midi file on my computer will sound quite different to say your computer. By
modulating the A.L. with data only would overcome the objection or
pre-recording a sound in air and reproducing it in another medium.
The mathematical model was predicted by a boffin and advisor to the program
at the Australian National Acoustic Laboratory and was surprised at the
results beyond that I can' offer any other details.
.
- References:
- Liquid breathing
- From: Charl_from_Lexicon
- Re: Liquid breathing
- From: Stuart
- Re: Liquid breathing
- From: John Schilling
- Re: Liquid breathing
- From: Stuart
- Re: Liquid breathing
- From: John Schilling
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