I can not possibly imagine that a group of soldiers in the heat of battle, fighting for their lives using things like metal weapons and armor (that make quite a racket when banged together) are likely to even hear the commands hollered by a nobleman standing THIRTY feet to their rear and think it even less likely that they would much care.
Herman stumbled as one of the Evilites bashed their sword against his shield again. Somehow, Herman thought he has heard Sir Noisy yelling something about "left". Move left? Face left? Herman did not spend much time thinking about it either. Herman had more immediate problems. The damned Evilite before him was skilled, strong and determined. It would take all Herman had to not die in the next few moments. Unless Herman heard the unambiguous horn blasts that signified retreat, Sir Noisy could worry about "left" all he wanted while the rest of us just tried to stay alive.
Exactly, and exactly why a melee is generally not a very ordered thing, it is a free for all. Part of the success of armies like the Roman forces where that they were trained to maintain formation for as long as possible when a melee was joined, but even they had difficulties with communicating to a unit that had engaged in close combat simply because once that happens you are talking the sound of metal on metal and men yelling/screaming in general. It doesn't matter how close you are once this happens, chances are slight that any sizable part of the force will receive the commands, and even if they do how do they enact them when everyone is struggling simply to spot and react to the next angle of attack?
Even in modern warfare, with the exception of those nice demonstration forces where every soldier has their own radio, which is not a reality for most 1st world armies, orders from a lieutenant are next to impossible to "hear". We were trained to constantly look to the closest command element (corporal, sergeant, lieutenant) in order to receive good old hand signal orders once battle was joined, something that even many professionally trained and experienced troopers would forget to do once they had bullets and other ordinance to worry about. There is not nor has ever been any form of perfect communication with soldiers that are actively engaged in fighting, military doctrines generally accept this and strategy is based upon the assumption that once forces engage you probably will not be able to issue new orders.
