Helium

[:Ace:]

How does Helium make your voice more high pitch?

[shammydodger]

Presumably it is to do with the change in the wavelength of the sound waves as they pass from air into the helium. That is, the sound is refracted.

Unless my A level physics is letting me down! (And it could well be, because it is a few moons ago!)

[:Ace:]

HeHe, I should have thought of that actually since I'm studying Waves

[shammydodger]

Actually, I think it has indeed let me down!

Go to this site:

http://www.phschool.com/science/cpsurf/ques_he witt/QA07.html

[Space]

waves passing from air to helium ( or vice versa ) wouldn't change the frequency...

[shammydodger]

Correct. But if the speed increases and the frequency stays the same, then surely the wavelength must increase?

[shammydodger]

Ace

See this:

http://www.physlink.com/Education/AskExperts/ae36.cfm

The best explanation I've seen so far.

[Space]

yes, but pitch means frequency, not wavelength.

[shammydodger]

Yes sorry Space. I thought your first post was having a go at mine, although I hadn't mentioned frequency.

[Space]

Some of the explanations I found on the net say that the pitch doesn't change, some do.

http://www.phys.unsw.edu.au/PHYSICS_!/SPEECH_HELIUM/speech.html
On this page, the guy manages to produce the same note with both air and helium, and it sounds different. I suppose the pitch would be higher with helium if he didn't carefully adjust the note he produces...