Helium

Okay, on to element number 2.  Helium is the first of the so-called "noble gases" on the periodic table.  These are called "noble" because they are very stable and chemically unreactive, so they don't usually hang out with the common riff-raff of the other elements.  It was once believed that these gases did not form any compounds with any other elements, but compounds of xenon with fluorine (among other combinations) have been synthesized.

It's fairly common knowledge that inhaling helium will make your voice sound funny.  I have firsthand experience with this phenomenon.  When I visited COSI (a science museum in Columbus, Ohio) many years ago, one exhibit contained a helium tank to which you could attach a disposable cardboard tube, inhale, and sound like a chipmunk for several seconds.  I had so much fun with this that I tried it over and over again, and ended up with a tremendous headache, probably from a lack of oxygen to the brain.  I was probably fortunate to not pass out.  Oh...and when I say many years ago...I was about 25 at the time.

Why does helium make your voice sound funny?  Basically, since helium is much less dense than air, sound waves travel faster through it.  The pitch of your voice is determined by the vibration of your vocal cords.  This doesn't change, since your vocal cords vibrate at the same frequency no matter what you've been breathing.  But the timbre of your voice is affected by the vibration of air in your vocal tract.  If your vocal tract is full of helium, your voice will travel faster, and sound higher.  Or something like that.

So if helium makes your voice higher, what would a heavier-than-air gas make you sound like?  Here is a video clip from one of my all-time favorite shows - Mythbusters.



Now, if I could just get my hands on some sulfur hexafluoride - then I could hit those low bass notes at hymn sings.