At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.
The only one I know of is Audacity. What problems did it have?
This is a tougher problem than you would think. It's not extremely easy to just isolate one or the other. A lot of programs may have a button that claims to remove vocals, but it's really just using some specifics filters. Audacity is a great program for basic audio editing. And it's free! So I can tell you some basic techniques for isolating tracks: 1) Check the difference between Left and Right tracks. Audio files are stereo meaning there is a left channel and a right channel. When mixing, engineers will "pan" specific tracks to certain places: e.g. guitar to the left, piano to the right. This is why when you put on only one earbud, you may hear just portions of a song. This is a nice way to "isolate" certain tracks but it all depends on how it was mixed. 2) Use an EQ. This is pretty basic and consequently not too effective, but it can be used to smooth over some "rough edges." Basically, you know the human voice generally isn't lower than 1 kHz, so we can "cut" all frequencies below there. Basically this is just an experimentation process. 3) Phase cancellation! My favorite. I'll give you a quick rundown on how this works in case you're not familiar...
So say we have a sound. For simplicities sake, let's say it's just a sine wave (every sound is actually just a sum of multiple sine waves anyway). It looks like this: |dw:1334936525632:dw| But it would sound exactly the same if it was inverted: |dw:1334936573261:dw| They both have the same frequency and amplitude, so on their own, they sound exactly the same. BUT when we play them at the same time, they get summed together: |dw:1334936620144:dw| It's flat! No noise at all.
So we can use this to our advantage. If we isolate just a guitar portion of a song, "flip it's phase" (meaning reflect it over the x axis), and then play it over the top of a portion of the song that is guitar and vocals, the guitars should effectively cancel out, leaving just the vocals. This is commonly called "destructive interference"
Here's a better pic, heh: http://astro-canada.ca/_en/_illustrations/a4313_interference_en_g.jpg
SIbelius is a good music creator. I use it at school.
Amazing detailed explanation by @Mattfeury . All hail!!