Lots of physics involved. 90% of performers sound great with their mics at their hairline. That's location that the frequency response of the mics were engineered for.
The other 10%? Not so much. For a variety of reasons from lack of hair, extremely high hairlines, to dense bone structure.
From what I understand from Rent, it was a design choice. Other times its simple logistics. The last show I did 5 of the featured actors changed wigs 4 times during the show. No way to deal with that other tape their mics to theirs cheeks or wear an ear clip, other than hiring a specific stagehand to deal with each actor on each costume change, and risk a 75% likelihood that they're going to go onstage with a working mic.
"Why wouldn't i be able to hear them? They could just put them on THE TOP OF THEIR HEADS. No Problem."
As I've told many a performer on numerous occasions, "The mic picks up what you sound like, not what you think you sound like." I.e. it needs to be pointed at their mouth to sound best.
Actually, the lavalier mics used in theater are specifically engineered to sound best pointed at the mouth laying on top of a sinus the same way an acoustic guitar pickup is engineered to be placed on the top of the body facing the strings. If you put it anywhere else, you need to compensate with EQ which is, in most instances, a losing proposition.
(The headset mics like used in Rent, obviously, have a different frequency response more fitting with their close proximity to the mouth.)
Updated On: 5/1/13 at 09:22 AM