Recorder Played with Helium
I snagged a helium balloon from the Red Robin today at lunch and got my son to play a recorder note for me with air and then with helium. I should have had him play Twinkle, Twinkle or some other tune, but even just the one note was pretty fun. This is basically the same thing as talking with helium. If you used sulfur hexafluoride instead of helium, the note would be lower.