I know that many of you have problems understanding American English spoken. Well, the only way to learn to understand it is through practice. For that reason I recommend you to listen to this story written by Mark Twain and that has been taken from the site Manythings.org. There you can also find more activities and resources for learners of English. A good point of this activity is that you can read the words at the same time that you listen to it.
Here you have a complete list of all the stories you can here. I’m sure these resources will help you improve your listening skills.