As an aside, cousins of mine had a baby who was a bad sleeper, when she finally did nod off they were no scared of waking her up again they started to tiptoe around the place, its so bad now that I called one day and my cousin saw me coming up the driveway and ran out before I could ring the doorbell. I had to take off my shoes as I went in, wooden floors everywhere, so as not to wake her.
Best advice, is when they are so young, continue with normal noise routines, hoovering, music, doors banging, washing machine going etc as then they will get used to it and sleep through it when as they get older.