It is so fun to suck helium out of balloons but I have always wondered why helium makes our voices so high. Well now I know why! Helium is less dense than air which means sound waves travel much faster than usual. It can travel to around 900 meters per second. Wow that's fast! Fast moving, higher frequency sounds have more power as they float in the throat but lower frequencies get a bit lost. When we suck helium, it's actually making our voices just squeaky and flatter. I know it's fun to suck helium out of balloons but it can kill you. If you get light-headed from blowing in too much helium, it is your body telling you that you need more oxygen. This can lead to
asphyxiation. If you do have a habit of sucking helium out of balloons, you should stop. Here are the links from the websites and the picture: http://ilovebacteria.com/helium.htm
http://www.howitworksdaily.com/science/question-of-the-day-why-does-helium-make-my-voice-sound-high-pitched/
http://img.medscape.com/news/2012/ts_120315_balloon_helium_teen_300x225.png
