I think it's both directions. I baby sat a lot of babies before having my own and I learned two things from it. Firstly, a comfortable baby will not wake up for anything. Second is just just how much of the world we learn to tune out by adulthood.

That second one is important, babies dont have any understanding to base things on and everything is new. Which means that there a million possible ways to exhale that the baby has never heard you do before and it doesn't have an association for exhaling to connect those yet so that's one million strange noises that could be a threat just from you breathing. You may recognize ever creak in your floor, but do you realize ever distinct variant of creak that each creaky board makes? Because a baby can tell the difference and doesn't know what a floor or a board, or friction between wood and nail, or resonance, or even what sound is. All it know is it's never heard that before and it might be danger, better call for help.

For those dealing with babies like this, I have advice. Be noisy around your baby. Put a rocking chair on the creaky board, clear your throat while you hold them, burping and farting are a big one, we try to hide those socially and that's why we get those videos where dad burps and the baby looks terrified, all of a sudden safety person just made scary new noise, what the fuck do I do? You'd look at your parent the same way if they just casually opened their mouth and made perfect whale noises. Take them around the house and show them benal things. I used to walk my boy through the kitchen and open and close cupboards and drawers. Lastly, respong with nonchalance. If they get spooked by a noise and you run in worried that the baby is crying, they feel fear about noise, see fear in you and that tells them they were right to be scared and noises mean danger. If instead you're cool and collected, they see you're not scared so they don't need to be scared.