Why does helium raise the pitch of your voice, and why does nitrous oxide lower it?

Question

Why does helium raise the pitch of your voice, and why does nitrous oxide lower it?

In: Chemistry

Answer 1

Everyone here who says “it because it makes your vocal cords vibrate faster” is absolutely incorrect.

The vibration frequency of your vocal cords is determined by their length, not the speed of sound in the gas.

What the gassed do is change the resonant frequency of the sinuses and vocal tract. This changes the timbre of your voice, not the actual pitch.