I have issues with background noise, especially when I need to concentrate.  In college I used to sometimes wear a set of over-the-ear hearing protection earmuffs when I was studying.  Never outside my dorm room though, because I didn't want to be known as that guy.  Years later I was gifted a pair of noise-canceling headphones, which were pretty awesome except when the battery got low.  Around the same time I discovered the wonders of white noise, or more specifically brown noise which has a more calming tone. 

A related issue is my inability to sleep through any type of sound, whether it's talking in the next room or snoring right next to me.  I'm surprised it took me this long to discover, but standard foam ear plugs work wonders.  I end up wearing them most nights just so my stupid cats don't wake me up.  But they're also perfect for hotels and friends' houses with unfamiliar surroundings and unexpectedly early risers.  I wish I knew about these in college; I wouldn't have had to call the cops on the guy down the hall whose alarm went off for seven hours straight while he wasn't in the room. #lifestyle