A Conversation for Ask h2g2
drewbert Started conversation Nov 9, 1999
Well, I hate to start off a new thread by being pedantic and nit-picky... but...
I can't find the post referred to on the main H2G2 page today about why your voice gets higher after breathing helium. But it has nothing to do with the speed of sound being fasterin helium. First of all, sound would travel *slower* in helium at room temperature, because it's less dense. (Think about it: sound travels faster in water because it's more dense. sound travels not at all in a vacuum because it's not dense.)
And even if the speed of sound were faster in helium, that wouldn't account for an increase in pitch of the sound. The waves would just get to you a little sooner. [To change the pitch of a sound without physically changing the source of the sound, you have to be moving towards or away from the source (the Doppler effect).]
If I recall correctly, the real reason has to do with helium gas tightening your vocal cords, making them vibrate faster.
a visitor to planet earth Posted May 6, 2006
Divers use helium instead of nitrogen when deep diving to avoid the "bends". One of the side effects beside the voice effect is that they feel the cold more.
Hooloovoo Posted May 6, 2006
LOL.... only just noticed the date of the OP.....
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