It makes it sound high and squeaky, like a rodent from Alvin and the Chipmunks. But, surprisingly, inhaling helium doesn't actually change the pitch of your voice. Here's what it does to make your voice sound weird: ... The sounds are the same pitch, but their tone (aka sound quality or timbre) are different.

Can helium permanently change your voice?

If you've ever breathed helium and heard the sound of your voice, you've probably noticed that the effect wears off quickly. That's because the effect only lasts as long as there's helium around your vocal cords. As soon as regular air replaces the helium, your voice returns to normal.

Does helium affect voice?

Helium is lighter than air. Which means sound moves faster through helium than through air – nearly 3 times faster, in fact. So the sound waves bounce around faster in your vocal tract, which amplifies the higher frequencies in your voice. It's sort of like how speeding up your voice makes it sound higher.