I know that my partner really enjoys it, because he knows that he's pleasing me if I'm loud and we're talking dirty. It's gotten more natural with time. I was absolutely silent during sex at first, except for little gasps. Then again, my first partner was terrible.
There's also different kinds of "dirty talk." During hot rough sex, I'll say dirty things, but during sweet, tender sex, I'm more likely to say entirely different things, more romantic than sexy. It depends on the mood. But I'm always loud.