That nothing really works that great. All the software I've seen over the years (google vocal remover) merely muffle the voices.
I find it cheaper to head to the store and get the instrumental version. If you need just that one voice, then I fear you need to work with the artist or owner.
There are many that have wasted years tinkering with filters, but in my line of work, we go get it rather than tinker.
I need the vocals of a song to be isolated/extracted and do not have the time to learn Audacity and do it myself as the deadline for this project is fast approaching. If there is anyone who can do this for me, I am offering to compensate for any help provided. Interested parties should go to Youtube and search: "Gang Fight: A Bad Lip Reading of Rebecca Black". During the chorus of song, and throughout the end of the song, you can hear a man's voice in the background (It is the voice of the actual singer, behind the synthesizers and all). I need this man's voice isolated. If someone can do that for me, I am offering good money. Email me at firstname.lastname@example.org