There is also the fact that when you've played the game long enough, you're more able to predict this kind of things.
The soundscape of this game is gorgeous. It worked so well when I discovered the game ! Later though, through habits, I came to think that some details worked well. For example, the sound of the alien when he comes down from a ceiling airduct : in survivor mode, the alien has had many times the tendency to go to and fro from these airducts to the rooms, and in some occasions I could hear the sound being repeated ludicrously in a brief time, because Xeno wanted to dance, maybe ! ^^
Maybe the sound itself should have had one or two variations, accorded to variations of the Xeno in this particular area : remember the time in San Christobal when he comes down from an airduct in such a magnificently creepy way - he should be able to do so, in this stealthy way, in other contexts, so that you may not be able to tell 100% of the time when he has finally come down from a celling conduct.
The hissing sound, for example when the alien has sensed your presence (but is not entirely sure you're there or not) is priceless. So efficient and scary. I'm not sure about some other sounds (when he "doubts' or seeks you), which seem less "alien" to me and make me remember more games like Penumbra or of its kind.
As for the footsteps, I remember being petrified when, the night after my first playing AI, I heard the footsteps from the apartment above mine.
Thanks for the link Corporal Hicks ! Indeed they've done a tremendously good job. I'd love an Alien Isolation 2, and I'm absolutely sure they would surpass themselves and that the little "habits" of the first game would disapear in that context.