If you are working in absolute silence and start to feel uncomfortably, you can always introduce some custom noise, be it a rain sound or ocean shore or noise of any color you like. Feeling chatty? Take Bob to a cooler and chat what you want, he's a chatter, too. On the other hand, it is very problematic (and really rarely effective) to just stand up in the middle of the noisy room and ask everyone, however kindly you manage to do that, to shut up at least for ten minutes, because you absolutely cannot concentrate in this goddamn noise that's been driving you nuts since said Bob came in at 9:05.
The point being, I want to be in control of my sound environment. Preferably without the need of earplugs or bulky headphones or other extreme measures like showing up at 7 a.m. or staying late just to get some shit done when the office is finally empty. I cannot concentrate, cannot even think clearly if there is almost any kind of noise - chatter, music, phone talks nearby, traffic noise from the street when the window is open or almost anything else, including my own voice. I know a lot of folks that, like me, would rather spend a night in the forest than an hour in the open space office.
From some comments I presume that it is probably impossible to convey to some lucky people with their extreme tolerance towards loud sounds how excruciatingly painful constant, unavoidable noise may be, but let me try anyways: it is a real damn torture resulting in days of not zero but of negative productivity. It's been my worst enemy at every place that I've worked at (close second are constant distractions, but I think these two are cousins), to the extent that my only special requirement for any job or workplace now is: please, let me sit in a quiet place.