At the beginner level it might be a good idea to listen to every mp3 repetedly until you can clearly hear and identify most of the words used in it (and not just guess or suspect what's been said). It may take half a dozen times or even more, but it pays off in the end. It might be boring at times, but for me it had a better effect than simply listening (albeit a lot) to different tapes, most of which seemed like an undecipherable murmuring at first.