a better way to ear train:
1-learn to sing your bass parts. Pick a simple one, and sing it- doesn't have to be in the same octave or in pitch, just close enough.
2- play a simple triad and sing it. Then move it up a step and sing that one. Move it down a step and sing that, etc.
3- Now do not play, but sing a note. then find it on the bass. When you can do that, then move to singing two notes, finding them, then three, etc.
4- Once you get this far, try to sing an entire bass part, beginning with a verse, without the bass, even if it is something butt simple.
As you get better at this, you will start to recognize bass parts from recordings, and follow them a lot easier. The point is, you can't pick out a part until you can hear it inside your head. This process is called learning to internalize music. This is how orchestral composers can sit with manuscript paper and write out symphonies- they knwo the sounds so well, it is jsut a matter of imagining them then writing them down.