True, but so will a knock or banging on the door, even if it is locked.

I have an office room although most colleagues are in open office with low-wall cubicles. Still, I find I can get more done at the hours when office is empty.

I try to make the best of a bad situation - the ambient noise was a far bigger problem for me in my current location.

Lucky you, I'm the exact opposite. It's mostly quiet here, and relatively normal/plain/cheap ear phones remove the speaking around me. In that case ear phones are actually a distraction/nuisance; having to constantly take them in/out, people speaking to you having to constantly say "Sorry to interrupt", "just a quick question", because they're more aware of bothering you, etc.