how does our brain tell the difference between the tv and a floorboard creaking while your asleep?

Question

Specifically my 3 month old son who can fall asleep to a lullaby but as soon as I try to walk away and the floorboard creaks he shoots up like I just rudely awoke him

In: 1

Answer 1

The creaking is a new sound, the tv noise is an old sound. Your brain becomes used to old sounds and tunes them out, they are usually not a threat. But new sounds require attention as they might pose a threat.

Our brains evolved this way to deal with predators sneaking up on us. The sound of crickets to a caveman can be tuned out, but the sound of a leopard sneaking up on you will wake you up.