There are always sounds bothering me, even if they're not constant. In my current room, I can hear stuff outside regularly, and when the central air kicks on, that's a big annoyance that requires quite an increase in volume. Then there's the refrigerator and freezer in the next room. The outside noises and central air are nearly muted in the basement, where my system will end up, but I also plan on getting a projector, which will bring its own noise. Because of the open layout of the basement, I will still have the refrigerator's noise, and it will be in the same room, not the next room. I don't really know what to do about that. I also need to do what I can to isolate the noise from the rest of my equipment (especially when I'm using the Xbox 360 or PS3. It just seems that with each of these contributors, I have to raise the volume that much more to get all of the details.
