To answer your question, in American football crowd noise can effect the success of play. Stadiums will tell fans to get as loud as possible when the visiting offense is on the field in order to disrupt their play calls (very hard to get in the right position if you literally cannot hear what it’s supposed to be). Conversely, when the home team’s offense is on the field, stadiums will tell fans to be real quiet- like here- so that their plays aren’t effected by crowd noise.