while at an amusement park, you inhale from a balloon to make your voice higher pitched. A friend says that?

Helium does not make your vocal cords tighter. The higher pitch you hear is due to the different properties of helium, such as smaller gas molecules that affect the way sound is produced. There won't normally be damage unless done to excess. Then the cords will be sore as if you yelled excessively at a sporting event. So your friend is in error and can no longer be trusted with pertinent information having a profound effect on your daily life. Educate your friend so he can join in with us believers.

Because he's a dork?

Seriously, the He is chemically inert so is not reactive. What really happens is that the frequency of the sound that makes up your voice is changed in an air-He mixture so everyone hears a higher pitch.

once you talk, the sound is transmitted by using vibrating the debris interior the air till it reaches the ear. as quickly as there its grew to become into the noises we've come to comprehend. hence why sound doesnt shuttle in a vacuum, there is not something there to hold the vibrations. once you inhale helium and talk, the vibrations develop into swifter, and subsequently larger pitched considering that helium's density is below air. in case you took in denser than air chemical compounds, the vibrations could be slower and could sound decrease. For safety, helium, being much less dense then air, can get away your lungs truthfully. So respiratory in a occasion balloon to develop your voice for some seconds won't reason any everlasting harm. in spite of the incontrovertible fact that prolonged respiratory of helium could be undesirable considering which you will not get sufficient oxygen on your physique, and could asphyxiate. The denser gases, which in maximum circumstances are in common terms available in technology labs, are a lot extra risky and could in no way be carried out for a multitude of components, all of which might bring about intense section effects or loss of life.

I would say that the reason is that helium really cannot react with anything (it is a Noble or Inert Gas). The reason it lowers you voice is that it is less dense that air.