Our air is filled with whistling, idle death-threats (or our individual personalities toward hypothetical homicide of evil villains), argumentation over life-extension research, astrophysics and metaphysics, joystick/button-mashing, showtunes, random bouts of poetry, fake British/Russian/German/Australian accents, looney Tunes character revivalism, and sometimes we take our functions out back to beat them into doin' the Right Thing.
I can't stand mouse clicking and keyboard tapping, so a little music for background noise is nice. I can also open my window and listen to the cars on the freeway.
We keep the volume pretty reasonable during work hours so you can still pop on headphones and listen to your own stuff if you wanted to.
With that said, I have my headphones in much of the time.
Nothing some noise-cancelling headphones and white noise can't fix :)