Why does Helium, when breathed in, alter your voice box?

Question

How does it alter your voice box? Why does it make it sound pitch-high? I need the facts!

Answer 1

it alters the medium through which the sound is traveling... helium is much less dense than air (about seven-times less dense). its the same reason as why your voice sounds really low when you talk underwater... water is more dense than air

Answer 2

Talking after breathing helium doesn't affect the pitch of your voice.  It changes the timbre.  This is because helium is less dense than air, thus sound travels faster in air.  It has nothing to do with the vibrations of your vocal cords, but rather the vibrations in the air or in this case heluim.

For a more impressive party trick, try inhaling some xenon and talking.

Answer 3

Helium has a low weight, and thus low density (which is why it is used in balloons)

This is a different density from normal air, which changes the vibrations of the vocal chords. Altough the popular belief is that it changes the speed of the vibrations, it actually only amplifies the higher vibrations and quiets the lower vibrations.