Sulfur Hexafluoride Is Like Reverse-Helium For Your Voice
Inhaling sulfur hexafluoride means that sound will actually travel slower out of your mouth, deepening your voice. It also affects the notes produced by wind instruments. Because it's so much more dense than air, putting an inflated balloon into a container filled with the inert gas causes the balloon to "float," as if buoyed by invisible water.
from Nick Uhas
Key Facts In This Video
When moving through air, your voice travels at 343 m/s; when moving through sulfur hexafluoride, it travels at 134 m/s. (0:11)
Sulfur hexafluoride is about five times more dense than air. (1:55)
Sulfur hexafluoride is used as a filler gas in tennis balls. (2:54)