Jumping at a sudden loud noise is a natural fight-or-flight response. You can give "everyone" a shock with a loud bang, when they're relaxed and don't expect it
As for how NT's hear... I think I have a pretty good idea of the difference...
Normally I don't have problems with my good hearing. But, right now, I have increased senses, as a side effect of medication.
I hear so many subtle details, which I never noticed before. It's like all the barely audibly sounds are boosted to the same level as the typical audible sounds.
Some sounds, like doing the dishes (by hand) is really uncomfortable and almost painfully loud.
Yes all people jump to loud or just unexpected sounds but AS ppl pick up on sounds background sounds more- they don't habituate like NTs do. hearing the smallest things like the hum of the refrigerator etc.