I use earplugs when doing work in any environment that's not quiet. What's nice about earplugs is (1) it cuts off only a 'layer' of sound that I find inhibits focus and (2) your hearing adjusts; you can still hear virtually everything happening around you. Being in the city, I find myself actually sporting earplugs virtually everywhere I go .. There's just soo much noise.
Which earplugs do you use? I find that my ears get very irritated using earplugs for extended periods.
Sometimes, I will experience minor discomfort if I've pushed them too far in my head, but pulling them out just a little usually relieves any problem.
I've had them in all day (again), only taking them out once for a long conversation I had .. and I sleep with them too.
Honestly, reality in a city, IMO, is by & far way too noisy. And I don't think from an evolutionary standpoint, we're super-well-suited for processing (consciously or not) all the different directions of noise washing across us ..
Or maybe I'm just too easily distracted/overwhelmed ;)