If you breath in helium how does the helium give you a higher pitched voice?

Question: If you breath in helium how does the helium give you a higher pitched voice?
- Keywords:
  body,
  gas,
  helium,
  state,
  voice
Asked by 09masseyo to Claudia, Phil on 22 Mar 2013.
- Claudia Krehl answered on 22 Mar 2013:
  
  Sounds even those coming from our voice are wavelengths and the speed of a wave is given by it’s wavelength and frequency. So the frequency (i.e. how high your voice is) is equal to the speed of the wave divided by the wavelength. Helium is thinner than the normal air we breath so that sound can travel much more quickly. It actually travels 2.5 times faster than through normal air, so the sound of your voice is 2.5 times higher than usual.
- Phillip Wilkinson answered on 22 Mar 2013:
  
  You can also get the opposite effect, a really deep low voice, by breathing something that is more dense than air:

Question: If you breath in helium how does the helium give you a higher pitched voice?