Try this
Even though I produce rockbands this helpt me perfecting my inner and outer hearing quite a bit.
- Get your hands of a copy of Bach´s "Goldberg variations" (yes, baroque music) played by Glenn Gould.
- Listen to it every day for a month or two.
- After some time you start to remember and recognize parts and you can maby sing along separately melody, bassline etc just by repetedly listening to it.
When that happens, you know that something is developing, keep doing it over and over.
If you get bored, change CD, but not too soon.
Chao, Foxy