Noticing things others don't

I've noticed that I react to things a lot more than most people.

I flinch at sounds, or sudden movements even if they aren't that extravagant. I get easily distracted by things that I notice briefly flash in my peripheral vision. Noises and sights of a room seem to blend together into one and can often be overwhelming-- I thought this was a normal thing until people began to frequently point out my flinching (and even doing things like hitting desks to make me react), and I noticed that people aren't at all bothered by the sounds that I find loud etc. It's like all of my senses have been cranked up a few notches.

I haven't had any traumatic incidents in my life. In fact, my life's been pretty good so it's not subconsciously linking experiences to one and other. Does anyone else notice this happen to them?