Whilst playing, I and many others hear ambient noises around us that don't fit. Sometime's I hear a person drinking or eating, when nobody is there. I hear fences being bumped, when I'm in the middle of a forest. Zombies are the big one though. Constantly I'll hear zombies moaning and groaning, although no zombies are in sight. Sometimes the noise goes on and on, as if it were next to me. Other times the noise starts, but then cuts out before the sound finishes.