Do dancers wear earphones also?

[majrakun]

I noticed Shuya was wearing one in his left ear during the CDL07-08 Fated performance, but I checked the A'nation Fated, he didn't wear any (at least not in his left ear). I tried checking the other dancers, but I can't seem to see any earphones, I think! So, I was wondering, do dancers actually wear those earphones as well? Or just for solo dancers?

...Oh man, I must've been watching the dancers TOO much lately. >_>