Sulfur Hexafluoride

Most people know helium as a gas which is used in filling balloons and as a gas which can alter your voice, it raises the tone of your voice. This is because helium is light weight. But there is also a heavy gas called sulfur hexafluoride which does the opposite: it lowers the tone of your voice because of it’s higher density. See the movie below to hear what that sounds like. It is not fake.