Why do football coaches yell?

Answer 1

The players are wearing helmets which can make it hard to hear. Especially with all of the background noise. Not to mention you're on a timer and you can't be repeating yourself over and over.

Answer 2

they are shouting out to put people in motion(messes with defense or better sets up play), or call an audible( change play), or to pretend to call an audible... they yell out numbers, colors, anything....

Answer 3

American football quarterback players shout to communicate with the other players. He will often use a hut, hut, hut, before he accepts the snap.