Sound problem

[Hetrofi]

When i play wow, i turn my sound on and off. this is because i think its relaxing to listen to the background music and i love hearing NPCs talk ( lol ).
The only problem is i dont manage to adjust my sound so i only hear the music and the voices.
I know ambient sounds is the one for voices, but thats also the one for spells, so on boss fights, i can only hear parts of what the boss is saying.

EDIT:
can anyone help me so i only hear NPCs and music?

[dabros]

ok

[Ozzy Osbourne]

Yup