i know what you mean, i have six dogs that bark at anything that moves, and they pretend they can't hear you. come to think of it, if i'm getting distracted, as i am now as i should be study ancient, i go do some excercise or something that i enjoy, so when i do come back to my work i will feel more like doing it, and also your brain is more active so its not paying attention to the small(or big) sounds around you.....................
i have no idea if i answered anything, but hey, lifes like that.