Writers have to imagine entire worlds, people and situations inside their heads. Then they have to take those thoughts and put them on the page. It's a personal process, and because of that you have to know how to isolate yourself.
Tuning Out
Can you write in a noisy room filled with people? I can...because I can isolate. Clearly it's not an ideal writing situation, but I'm guessing that you don't live in a large mansion with lots and lots of rooms. I'm guessing you live in a normal-sized home, and that other people are sometimes around you.