Idk what kind of maps you were playing, but that to me sounds like either someone has no sound on (zombies tend to be loud bastards when they are about to shank you in the rear), or is fairly new to the zombies mode. Back in BO1's Kino Der Toten it was the golden rule to stay in the 1st room till the dog round, when that happens sprint to the MP40 room and get the MP40, survive for a while there till you have enough points to get set up and then roam around the map.
I'll rephrase what I said in that it's helpful to have communication when no one is really familiar with the map/mode, but with more experience comes a lesser need to communicate and its more like a well-oiled machine. At least for me that is. Then again I might be an elitist given my experience with the mode/genre in general :P