Christina Elizabeth, a professional opera singer, offers an extra squeaky "Deh Vieni Non Tardar" from The Marriage of Figaro. Her already extraordinary vocal range is made only greater with the addition of helium. It's delightful! I would sit through an entire opera if it was performed this way.
-via The Mary Sue
I do wish people who do these stunts would specify for potential copycat viewers that the inhaled gas is "Heliox" - a mixture of helium and oxygen. Inhaling pure helium is dangerous and potentially lethal.
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