For years I had been under the impression that without access to a multitrack studio master tape that cleanly removing vocals from a song was pretty much impossible. I have been told that I am mistaken. Apparently there are hardware (and possibly software) devices that will do just that with any song using just the finished/published music. This has me confused, how can this be? From what I understand the vocals in a song are so intertwined with the rest of the music that you can’t isolate them and remove them without affecting the rest of the song. Can anyone set me straight on this? Many thanks in advance!
If you take the stereo tracks and make them out-of-phase, everything in the middle, including the lead vocal, will disappear. If you then filter the out-of-phase tracks so that only the stuff in the vocal range is eliminated, you can pretty much get rid of what you want and keep the rest.
There used to be a device called the Thompson Vocal Eliminator that did this–I have no idea if it is still available.
Calling it “cleanly removing” might be an exaggeration. 
The frequencies of the human voice are spread right across the human hearing range, and so removing them completely would appear impossible. However, most of the energy resides in the fundamental (the sine wave which forms the “pitch” of the note). Presumably one Fourier Transform the song into the frequency domain, remove the frequency spike at the pitch of the melody, and transform back to rid the song of most of its vocal volume. However, all other instruments would lose this information also.
Just a guess, mind.
Pretty much what I had always thought, thanks guys. The Thompson Vocal Eliminator is indeed still out there and they claim some pretty good success. I wasn’t all that impressed with their demos, but it could be useful. So far it looks like I was right though, you can’t completely eliminate the vocals but you can mask them pretty well.
Come to think of it, even getting rid of the fundamental wouldn’t work - you’d hear the vocals with a “telephone voice” quality pretty much just as loud really.
Yeah, stereo manipulation must be it.
I’ve heard these things in action. They do effectively muffle the vocal, but can’t remove it. You also lose a fair slice of the mid-frequences, so the whole thing sounds rather odd and certainly nothing like a clean instrumental. It also depends on the track “playing by the rules” with the vocal at the right frequences and in the middle of the stereo image.
I remember seeing a demonstration of a system that could do this quite some time ago on the BBC science magazine programme Tomorrow’s World.
The way they explained it is that, for a track recorded in stereo with two microphones (or mixed to appear that way), the system would look for features that were identical in frequency and amplitude on both channels, then eliminate these, effectively cutting out whatever was directly between the two microphones.
By adjusting this so that you’re finding features that have the same frequency on both channels, but the amplitude of one is consistently say, 80% of the other, you’re cutting out something that was not centrally positioned between the two mics.
Something like that, anyway.
I’ve produced and recorded music for years, the answer is no.
Nocool mentioned a good technique, but as he already stated, it wouldn’t be the cleanest.
Is there something in particular you need to do?
It was more a philosophical discussion than a need that I had. A friend of mine at work is into audio production and was asking around. My first answer was essentially correct, no you can’t remove the vocals entirely while leaving the song untouched. Thompson’s website makes some interesting claims about their equipment:
I dunno, I wasn’t impressed by their demos. Thanks again all!
I had a Panasonic portable CD player about eight years ago that, when the headphone jack was slightly loose, would cut out most of the vocals to the average song. Of course, it would eliminate a lot of other tones too, but the basic melody and instrumentation was there for my lo-fi karaoke pleasure.
My first stereo system was a 1978 Yamaha Receiver with a 1993-ish Sony CD player hooked up to it. For some reason, whenever I played a certain Beastie Boys CD, the song would come on, but the vocals were gone. Damndest thing, I never could figure out why–it never happened with any other song I ever played on it…really odd.
Here’s a diagram of how to achieve OOPS (out-of-phase stereo). May not work with all stereos. I’ve never tried it, but I ran across this site the other night.
Possibly useless tidbit: Nero CD burning software has a Karaoke filter. I haven’t used it (That’s what makes this tidbit possibly useless), but if it were to work how I imagine, it would be mighty cool!
Winamp has several free third-party plugins available that do this.
The results are not impressive but fine for amateur karaoke purposes.
My brother’s stereo system had a Karaoke mode which would filter/suppress vocals. It worked much better for some songs than others.