WMP does not have any tools for adjusting audio output. It is a file player. It has volume controls.
If you want to do a dodgy job, there is a program called Audacity, where the blue wavelines are the only thing you have to go by.
You would need a sophisticated audio editing suite in order to separate vocals from a particular audio file and I doubt any non-commercial suite could do it on-the-fly.
Goin' Fishin' (Some day)