I have found that whatever peace blocking noise gives you, it is more than offset by the paranoia of being watched or the terror of people sneaking up behind you.
For me visual distractions (even if it is just people walking) are a lot worse than noise. I can tune out the chatter but whenever I feel or see movement around me, my head snaps to attention to find out what it is. Some evolutionary thing most likely
I have had this happen to me a few times. Really into my work with my ear phones & music playing, can hear nothing besides my music. Turn to the side and my co-worker is there waiting on me to go over something. Scares the *$#$ at of me every time.
FWIW, I've seen some people attach a small convex mirror to the edge of their monitor to avoid this kind of surprise. I'd expect this is just trading audio distractions for visual ones, though.
