It's also considered unsafe.
For example: When I used to help ref for local fields during casual rec. play, I once had to tackle a guy who was deaf in both ears due to not being able to hear that his opponent called himself out. The eliminated player yelled "out" loud to those all within proximity, but started to take off down field without plugging his marker, nor raising it - just took off in a hurry to leave the field. The one hard of hearing however, didn't understand. Now, his actions were very understandable, considering. Though, surely you get the idea
Plus, you're at risk in accidently over shooting a player to a point in really upsetting him/her, as well as possibly everyone around you because of it.