Ok what about helium.......I learned something new!!!...this and after doing shoulders bras that hook in the back are a BITCH!!!
"Helium is a non-reactive or noble gas. It does not cause any physiological or metabolic changes in your body.
In order to understand why your voice changes when you breathe helium, you need to understand how your voice actually works.
In simple terms, air moving past your vocal chords causes them to vibrate. By changing the shape of your mouth and throat, you sculpt the sound into normal speech. You change the pitch of your voice by making the space in your throat larger and smaller, and, to some extent by increasing the tension in your vocal chords.
Now we get to the science. In physics terms, your throat is a resonating cavity (this also applies to pipe organs, flutes, saxophones, and other wind instruments). There is a classic formula that describes these situations: velocity = frequency * wavelength. What this says is that the velocity of a sound wave in a resonating cavity is determined by the frequency and the wavelength of the sound. Now what is interesting about this is that the wavelength is determined by the shape and size of the cavity (your throat and mouth), and the velocity is determined by the density of air (which is constant).If you change the shape of the cavity you will change the wavelength which will in turn change the frequency.
Now the fun part. The only fixed part of the equation is the velocity. This part refers to the speed at which sound travels through air. What happens if you replace the air in your throat with helium? Well, it turns out that sound travels almost twice as fast through helium as it does through air. Ah ha! The equation tells us that the velocity has to EQUAL the frequency multiplied by the wavelength. Well, the wavelength is determined by the shape and size of the cavity. That part didn't change, so the frequency must change.
You experience this effect when you breathe helium. You try to talk in a 'normal' voice, but the gas in your resonating cavity has been replaced. Your brain puts your mouth and throat in the usual positions for making words(the size and shape of your resonating cavity remains fixed), and you start talking. helium has changed the velocity of sound in your throat, and as a result the frequency of the sounds that you produce are twice as high as normal.
I hope this helps you understand how helium affects your voice. Remember, when you breathe helium you are depriving your body of the oxygen that it needs. Always take a few breaths of air immediately after breathing helium. If you breathe it for too long, you will start to feel light-headed and dizzy. Prolonged breathing of helium could even cause suffocation! "