Everyone imagines what it would be like to live in the International Space Station for a few months, but many don't take the noise level into consideration -- we kind of assume that since it's in space, things are a bit quieter, even with all of the machinery and gadgetry that surround the astronauts, but it's actually quite the contrary.
Commander Chris Hadfield recorded 16 seconds of ambient noise aboard the ISS, and it sounds like a data center full of servers and cooling equipment -- in other words, it's not as quiet as you'd expect. Then again, it's not too surprising since there's a ton of equipment on board, like all sorts of machinery, computers, and testing equipment.
Hadfield notes that the quietest places in the ISS are the astronauts' sleep stations (obviously), since they're essentially "small insulated pods" that can close up to block out most noise. However, Hadfield also notes that the bathroom is the loudest place on the ISS, so if you really want your privacy and a quiet place to go to, don't resort to the toilet.
Much of the noise comes from the fans and air pumps necessary to keep the astronauts breathing, so we don't think many of the astronauts on the ISS complain about it. Hadfield says that the ISS is pressurized to sea level pressure, since the thicker air helps keep all the machinery cooler and "is more natural" for the astronauts.