[eengstrom]

I too have difficulty focusing in noisy environments. If you're interested in filtering environmental human-sound out while still being able to listen to music, or hear an approaching train, check Mack's Earplugs out.

Clickable: http://www.macksearplugs.com/details/ear-plugs-for-loud-musi...

I use them when flying, or working in a common space. Worth buying in bulk and keeping. They can stay in comfortably on a 13 hour flight without impairing your ability to hear someone approaching/speaking to you.