I have heard those noises even in a superflat world. I have been really creeped out by them and sometimes a hear a high pitcched noise that sounds kind of like a scream. I will even hear what sounds like an enderman teleporting. Very weird and unfortunately, I don't know that the cause is. This happens on any world I play. My older sister says it's just the sounds the game makes and not anything else.I do not believe her because when my PC was out. I played Minecraft on my ps3 for two weeks and I haven't once heard those noises. Needles to say, I will not play Minecraft till I know the cause.