I bought noise isolating headphones today to deal with office noise. I heard very good stuff about Audio Technica ATH-M50X and they are really good indeed. I can definitely recommend those.
(Yes, gun range ear mufflers will work, but you might look awkward. I have a sets of those when I really need to concentrate)
Here's my recommendation:
Shure SE215-K. In ear studio monitor. amazing noise blocking ability, and, you can play some music to boot. I have literally wore mine down from years of office/motorcycle/road trip use. They have replaceable cables too.
Caveat: These can be uncomfortable for prolonged use (I'm talking ~20 hour road trips) as they're in-ear, but seriously get a set. Now that they're $99 on amazon, vs. the $299 I paid for them years prior -- it's a no brainer. In fact, I'm going to get another set this very moment.