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Author Topic: Why does Helium make my voice pitch change ?  (Read 52040 times)

neilep

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Why does Helium make my voice pitch change ?
« on: 11/06/2004 22:08:52 »
My kids went to a party and I went too and had fun breathing in helium....in fact I'm still inflated and the pitch of my typing is still high (can you tell ?)..errrrrrrrr.....anyway....why does it do it ?....and is it harmful ? *cough splutter gag*

Ylide

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Re: Why does Helium make my voice pitch change ?
« Reply #1 on: 12/06/2004 03:44:28 »
The pitch and tone of the sound by your vocal cords is partially affected by the way air moves through your throat.  Note that you can't talk if you stop your breathing.  Helium diffuses at a different speed than air (mostly nitrogen and oxygen) consequently when you exhale a baloon full of helium, its faster rate of diffusion causes the pitch change in your voice.  Helium is inert, it won't hurt you.  There are some minor risks involved in depriving yourself of oxygen, but a balloon or two here and there isn't going to hurt you.



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valley

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Re: Why does Helium make my voice pitch change ?
« Reply #2 on: 12/06/2004 08:22:32 »
It's because Helium is lighter than air. Remember that (like a guitar) the sound comes from the vibrating air, not your throat/strings. I'm not entirely up on this but I guess it must be either that the Helium vibrates more because it's lighter (erm?) or because your meaty bits can vibrate faster as they only have to push the light Helium around. Anyone?


Ylide

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Re: Why does Helium make my voice pitch change ?
« Reply #3 on: 13/06/2004 06:48:38 »
Vibrating solids propagating energy as sound through a fluid medium is not the same thing as the fluid medium vibrating.   Helium as a medium would allow faster propagation of sound waves because of the lighter mass and smaller size per helium atom relative to nitrogen/oxygen atoms, causing an increase in pitch.

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chris

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Re: Why does Helium make my voice pitch change ?
« Reply #4 on: 13/06/2004 08:07:24 »
The question of why helium affects the pitch of your voice was a "Question of the Week" about 6 months ago.

Here's the answer :

Here is the answer to last week's QOTW - "WHY DOES HELIUM MAKE YOUR VOICE GO FUNNY ?"

If you imagine your throat as a bit like an organ pipe, when the organist plays a note, one cycle of a wave, with a wavelength approximately the length of the tube, is generated inside the pipe. So when you talk you produce sound waves with wavelengths determined by the length of your throat.

The speed of a wave (c) is given by multiplying the wavelength and the frequency together (c=l.f) and this can be re-arranged to find the frequency of the sound wave (in other words how high it sounds) (f), thus : "frequency = speed divided by wavelength" or f=c/l.

But helium is less dense than the other consitutents of air and so sound travels much more quickly in helium (900 metres per second) than in air (350 metres per second). Substitute these numbers into the forumla we got above (f=c/l) and you get a value for f (helium) 2.5 times greater than f (air). As a result you voice sounds 2.5 times higher when you breathe helium.

Conversely, if you were to breathe a denser gas than air you could make your voice sound much lower.

Divers breathing a helium-rich mix (to overcome the problem of increased gas density at extreme depths) talk to their support crew using a "helium voice unscrambler" which reinforces the lower notes in their voices whilst suppressing the higher tones so that they can be understood.



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neilep

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Re: Why does Helium make my voice pitch change ?
« Reply #5 on: 13/06/2004 11:35:23 »
Thanks Chris.....seems I just missed that topic when I joined...and thanks to everybody else for the answer......and presumably it IS safe to breathe too as Cannabinoid mentions.....so, as long as we top up with oxygen we could quite happily survive on a nasal diet of happy helium !...Ta

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chris

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Re: Why does Helium make my voice pitch change ?
« Reply #6 on: 16/06/2004 07:14:40 »
Actually I've noticed a big boo-boo with this answer. I'll have to sort it out - the answer is not correct. When I have 10 minutes I'll do it.

Chris

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Bert

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Re: Why does Helium make my voice pitch change ?
« Reply #7 on: 28/12/2004 20:45:22 »
I hope Chris has had his 10 minutes to find the problem with the answers so far. Simply saying that the speed of sound is greater so the frequency is higher does not explain the phenomenon.  Your vocal chords are vibrating at the usual frequency, so the frequency could be the same, but the wavelength of a note produced could be greater (to make speed = (frequency x wavelength) correct)

neilep

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Re: Why does Helium make my voice pitch change ?
« Reply #8 on: 28/12/2004 21:19:38 »
Thanks Bert

...Yes Chris...at the time of this post,your ten minutes were up over 6 months ago !!!....else, you must really be so attentive that the time you're taking to correct the big boo-boo is a declaration and example of fine dedication....*sigh*, wish I could be this committed to such perfection :-)

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chris

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Re: Why does Helium make my voice pitch change ?
« Reply #9 on: 30/12/2004 10:38:35 »
Thanks for resurrecting this. Actually, I did go into it, but then used more than my 10 minutes and hence had no time left to write up the correct answer.

In fact the pitch of your voice remains the same when you breathe helium, what changes is the 'timbre' (nothing to do with trees).

This is most noticeable when you sing whilst breathing helium.

When I have 10 minutes (!) I'll dig out a good link to a site that has audible demonstrations and a satisfactory explanation.

Chris

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daveshorts

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Re: Why does Helium make my voice pitch change ?
« Reply #10 on: 24/03/2005 12:23:00 »
I think the link Chris wanted was:
http://www.phys.unsw.edu.au/PHYSICS_!/SPEECH_HELIUM/speech.html

I think it basically says that your voice system consists of two parts your vocal chords/folds and your throat. It is a bit like a very short trombone, the vocal chords are like your lips in a trombone and the throat like the tube.

 The vocal chords vibrate produce lots of harmonics f,2f,3f etc. (where f is the lowest frequency you produce)  setting the base frequencies of the voice.
Your throat is a resonator, so it will vibrate better at some frequencies than others, so it will affect the  relative strength of each of the harmonics.
eg if you make your mouth longer when you are humming it will make the lower harmonics stronger and the higer ones weaker sounding deeper. The relative strength of these harmonics are called the timbre.

Because the speed of sound is much faster in helium it is like halving the length of your throat (but less painful). The high harmonics are strengthened and the low ones weakened, so your voice sounds higher, without actually changing the frequency of your vocal chords.

Dave

ps It also has the perculiar effect of giving me an ozzie accent... I am not sure why
 

anthony

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Re: Why does Helium make my voice pitch change ?
« Reply #11 on: 09/05/2005 11:02:47 »
My first post!

When I assisted in the training of ambulance technicians, and during training for myself, I took a few puffs of Entenox, nitrous oxide and oxygen mix, 50/50. The tone of my voice went down. The mixture is more dense than air, so agrees with many of the suggestions proposed so far. You could try the experiment for yourself, though perhaps best to avoid controlled medicines, try argon, the same as you would a helium balloon.

I was going to post a suggestion, but then I realised that Daveshorts gives an explanation I can't find fault with.

chris

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Re: Why does Helium make my voice pitch change ?
« Reply #12 on: 09/10/2006 14:21:35 »
I'm a bit worried about Anthony's suggestion to try breathing argon to see what sort of effect it might have on voice timbre. Argon, being so much heavier than air, is likely to sit at the bottom of the lungs, displacing the light gases (e.g oxygen) upwards.

I suspect this might have a deleterious effect on consciousness...

Chris

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bostjan

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Re: Why does Helium make my voice pitch change ?
« Reply #13 on: 10/10/2006 01:40:50 »
The speed of sound/frequency explaination is incorrect, because the wavelength of the sound changes through various media, whilst the frequency remains the same.  Otherwise, you would only hear very high frequencies when you hold your ear up to a wall to hear what was on the other side, because sound travels faster through a wall than through air.

The timbre certainly does change.  This is why you sound more like a duck than like a mouse.

syhprum

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Re: Why does Helium make my voice pitch change ?
« Reply #14 on: 11/10/2006 14:17:53 »
The 'Helium' sold for inflating balloons is a mixture of Helium and Nitrogen to reduce the cost as the full lifting potential of pure helium is not needed for toy balloons.
If you measure the actual change in pitch you will find it much less than that which deep divers produce on the genuine article

syhprum

 

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