I've encountered the "truly quiet" environment a few times, and really found that the worst of all: Every noise of the most meek activities, from the clicking of a mouse button to the quiet clearing of a throat, rings throughout the area. After you realize that, concerns that your own minor noises are irritating others puts you on edge, as you try to click the mouse button as softly as possible, ignore that tickle in your throat, etc.

If there isn't good sound suppression, I've found the best alternative is sound camouflaging -- the HVAC fans always distributing noise, or even something as ridiculous as an area fountain. Something to make a base level of white, ignorable noise that stops you from focusing on the small noises.