• Question: Why is it when you inhale helium your voice goes high

    Asked by dbryce to Andrew, Daniel, Hayley, Natalia, Peta on 21 Nov 2011.
    • Photo: Hayley Smith

      Hayley Smith answered on 21 Nov 2011:

      The pitch (frequency) of your voice is caused by air in your voice box (I’m sure that has a more technical term, but I don’t know it…) and that pitch will depend on the air in the voice box and how big the voice box is. So I guess (this is just a guess) that the speed of sound in Helium is faster than that of regular air and as such you have a higher pitch? Or maybe it does something to reduce the size of the voice box, this would have the same effect, but my first answer seems more likely…

      Maybe one of the other scientists knows for sure though…?

    • Photo: Daniel Scully

      Daniel Scully answered on 21 Nov 2011:

      High sounds come from sound waves which are very short. Low sounds come from sound waves which are very long.

      The length of the sound waves your voice makes depends on how dense the gas in your throat is. You need dense gases in order to make long sound waves.

      Because helium is lower density than normal air, all the sound waves your voice makes are shorter, so you sound higher.

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