One thing that I was really worried about when preparing to move to Seoul was the noise. So worried, in fact, that I didn't even blog about it--it would've made it too real! I have never lived in a city--the closest I've ever gotten was Ellensburg on a big party weekend--and it's a small town!
I was worried that there would be sirens all the time, that people would be out yelling down the streets in the middle of the night, cars honking, and that I would never sleep again! I even brought ear plugs with me for when I got desperate. Thankfully, my fears were completely unfounded! I'm sure there are parts of town where some of these things are realities, but we actually live in a very quiet apartment complex and in a quiet neighborhood. Honestly, I think the only noises I use the air conditioning to drown out are the noises of my children opening their doors and walking around on the wood floors (and that is mostly because I hear it whether it is really happening or not...gotta love my "mom ears").
I will say that being from the Northwest, we have never experienced the constant hum of the cicadas, and they did take some getting used to, but I'll take that over people any day!