Extremely loud noise really bothers me. I keep earplugs in my backpack for concerts, movies, sporting events, etc. and occasionally just walking around downtown. I even wear them when playing guitar at high volumes - it's harder for me to concentrate on pitch when my ears are ringing otherwise.
It's really too bad that we've become so used to the aural assault. Leaf blowers, car alarms, traffic noise, construction, lawn mowers (although the electric one that we got a few years back is sooo much better on this front), air conditioners, aircraft, etc. It definitely puts me on edge if I can't escape it, and I bet it makes other people cranky too.