Tina, sounds like you have a different learning style, don't learn through your ears :-)

See if you can learn what your learning style is and then "translate" what the lectures cover in a way that you can "hear" them; visually, sensually, etc.

http://www.ncsu.edu/felder-public/Learning_Styles.html

You have to figure out a way that works best with how you learn. It's not you! It's just that the lectures don't match what you're good at, kind of like how some people are good at math and others English? You might want to go to your school's study/tutoring center, they might be able to suggest ideas on how to organize your listening so you can get more out of lectures.