Listening to the sound of the breath inside your head seems to be more of a concentration technique. So I wouldn't encourage it, I would probably want to get more to feeling the breath.
With the other one; usually if it helps to settle you in I encourage people to begin with a few deep breaths, just as long as you allow the breath to become normal and natural after a set amount of breaths. This can be very helpful. As long as we don't continue forcing the breath for the whole session, because if we do that then there's too much "me" and "I" involved and will power, rather than developing the gentle flowing awareness of things as they are. So for concentration it can be helpful to do this in the beginning to settle into the session.
However with the first one, perhaps if the mind happens to be very, very restless you can do it for a little while, but I wouldn't encourage it. This is because with listening it's very easy to get mesmerized by listening and we may just flow along with the sound, absorbing into the sound of the breath. This can actually work against you, in that you may start to like this pleasant sound, and then develop aversion to unpleasant sounds.