Anyone who has been to a little kid birthday party knows the phenomenal comic power of helium. This most hilarious of gases is responsible elsewhere for the power of the sun, but its most important function is making people sound like Alvin and the Chipmunks rejects. But how exactly does helium affect the human voice? And can other gases have distinct, equally ridiculous results? The fine folks at io9 have done some research on that there Interweb and put together an explanation. At last, you can understand the thrilling science behind your childhood antics:
The common misconception is that, because helium is a lighter element than the main components of air, your vocal chords will vibrate faster if immersed in it. This makes a certain amount of sense. People move faster through air than they do through heavier stuff like water. Less resistance should enable vocal chords to move faster as well.
As it turns out, though, vocal chords vibrate at pretty much the same frequency no matter what gas rushes over them – though chlorine would eventually pose a problem. That factor isn't what changes the sound of your voice.
There are two major things that determine the sound of a person's voice. The first is the size and shape of the vocal chords themselves. The other is the shape of the throat that the air passes through. Vocal chords are not the precision instruments many people imagine them to be. They create not a single note, but a jumble of sound. Of that sound, certain notes are emphasized.
Specifically emphasized are the resonant notes. These are the notes which ‘fit' inside the throat.
How does helium change that? Sound travels faster in lighter gas. Because helium hangs out at the top of the periodic table, while nitrogen, oxygen and carbon dioxide, major components of the air we breathe, are heavier, sound will travel faster in a throat filled with helium than it will in a throat filled with air.
When you breathe in helium, your regular voice is joined by a whole host of new, higher resonant frequencies. You'll still be able to sing or speak the same note as you do with regular air, but because the higher frequencies are included, your voice will sound high, odd, and hilariously funny to drunk people.
Amaze your kid sister's friends with this information next time you all gather 'round for a slice of Spongebob cake. io9's article has a lot more interesting and potentially deadly ways to explain this and other phenomena, so get on over there for your daily Bill Nye fix.
