This is how dorky I am...
I have to read a lot for my major and if I'm cramming for an exam, I have to have absolute silence when reading, but that's hard to come by with obnoxious neighbors. So, I use white noise. Well, no, white noise is too high-pitched for me, I use pink noise (lower... pitch? Not as ear-splitting... ;)).
...but it might be child abuse to blast white noise at your sons. ;)
But just in case anyone else needs it (http://www.simplynoise.com/
is great. They have white noise, pink noise, and brown/red noise they even tell you how to loop it seamlessly. It doesn't seamlessly loop on my MP3 player, which is a shame because it's impossible to do some last minute intensive studying in a classroom.)
I find it useful because it's not completely silent so it drowns out distracting noises, but it sort of blends away as you're studying so that it's not obviously playing. I honestly find it very useful to help me concentrate, but I think there might be some people who would find it obnoxious.
Classical music isn't everyone's cup of tea, but I love classical music when studying because there are no lyrics (for the most part). Though, I do sometimes get distracted even with classical music.
I also agree about ambient music. (Though ambient music has a tendency to make me sleepy. ;D Of course, like I said, I'm usually cramming last-minute. Like now. Shame on me.)