I'm gonna second what steve1011 says. If it's just dampening down noise you're after good earplugs are probably better than the best noise canceling headphones.

I'm gonna second what steve1011 says. If it's just dampening down noise you're after good earplugs are probably better than the best noise canceling headphones. I wore industrial grade earmuffs and earplugs most all day long when I did metal work. That's not the same as wearing them in an office environment all day but I didn't find earmuffs terribly uncomfortable and I just looked at few newer models that look pretty close in design and weight as the Bose headset for about $30. Both plugs and muffs have pros and cons. Plugs are less conspicuous, and muffs are easier to get on and off. My own experience is that they work about the same (if both are high quality) and I generally wore both when doing metal work because the loud hammering and grinding I did was especially damaging to our hearing and there was a very noticeable difference than when using only one of those. The earplugs I used were made out of "memory foam" (like the bed mattresses use). There are other types I tried but they were not near as good.