This is a load off my mind now...I really had a hard time pulling out the bassline of songs when I first started....well I Still do sometimes...but I haven't been playing for that long (1 1/2 years). I think I sometimes mix up the bass drum with the bass. What I found to help me was to wear headphones, someone brought this up already but I thought Id repeat it again. Before going to bed or while in bed(i sleep with my headphones going. What Can I say...I Eat, Sleep and Drink music) I would lay there just trying to concentrate on the music, and nothing else....I block out all the singing and just listen to the music....Then i would try to pick up the bass and just focus as hard as possible on that...you will loose it once and awhile but as everyone has stated, with practice you will get better. Now I Try to listen to how the different instruments relate to each other, and see how they complement one other. I listen to a lot of Tool and Classical music when I do this...so it can be quite interesting to see how everything combines together to make the overall sound.