From a 2012 NYT article about what orchestra conductors are doing with their hands, which I found after identifying with Rex Parker, who had trouble with a clue in today's crossword puzzle:
The clue on WANDS is so hard! (68A: They may be waved at concerts). I assume these are the metal detector WANDS they might "wave" over you as you enter to make sure you're not packing? I can't imagine what other WANDS could be at issue. Well, whether it's security WANDS or some other WANDS I don't understand: hard [UPDATE: so ... everyone says it's conductors that wave WANDS. I'm sure this is right, but I am also sure this is wrong. Conductors. Wave. Batons. They aren't. Bleeping. Magicians. Thank you.]The only "wands" I could begin to think of at concerts were those damned glow stick things.