Isolation of individual voices on acapella recording

Hi. New to this forum. I am looking for a software, should such exist, that will allow me to isolate each of the voices on an acapella (no musical instrument accompanyment) musical recording. Legally purchased items. Purpose is to separate the bass, alto, soprano, tenor, and lead to help teach kids these individual parts better by allowing them to hear what THEIR parts alone in a song are supposed to sound like. Thanks.

I doubt that it can be done. Even though voices sound in different registers, there is a huge crossover in the harmonics of each voice. Where voices are singing in the same rhythm it will be very difficult to separate out which harmonics belong to which voice even with the best and most expensive software.
This screenshot shows the spectrum of three voices singing an “ooh” sound. The multiple horizontal lines are the harmonic overtones of the voices, To separate out the voices you need to be able to match the right overtones to the right voice.

"You can’t un-fry an egg or un-bake a cake, and you can’t un-mix a song."

That’s why pros use [u]multi-track recording[/u]… By recording each instrument and voice (or sometimes a group of voices) isolated on a separate track, each part can be adjusted, processed, and edited separately, or re-recorded separately. Once the tracks are mixed-down to stereo (or surround, etc.), you only have the left & right channels to work with separately. (There are few “tricks” you can do with the phantom “center” channel, and you can make some adjustments with with filters & equalization. But, there is a LOT of overlap between different voices & instuments).

It’s also one of the reasons multiple microphones & mixers are used live… The sound engineer can adjust the relative levels of each mic. If there is just one mic in front of a band or ensemble, the sound engineer can only has one volume control to adjust the sound as a whole.

Is it at least possible to diminish the volume of the lead voice only? I’ve been working on a transcription of Rockapella’s arrangement of “Oh, Pretty Woman” for almost a week, and although I’m almost done, I can’t discern the lyrics of the backup vocals in certain spots to save my life! At least 60% of my time I’ve spent working on this transcription has been trying to find a solution to this problem, or in getting the help of others, and I have been met with no success whatsoever, and my patience, as well as my temper, has already grown thin several times over, almost to the point of despair.

If this currently isn’t possible, then fix that issue ASAP and email me when you’ve done so. I cannot sanely tolerate failure with this much longer, as I am in a hurry to get this done before the 7th of January. Don’t waste time asking me why, as I will only see it as an excuse to avoid the question, and that will only make me angrier.

Thanks in advance. I hope you guys are the ones who FINALLY relieve me of this frustration.

Sometimes. It depends on the recording. See: Tutorial - Vocal Removal and Isolation - Audacity Manual

Spleeter can remove the bass & handclaps, but it can’t separate the lead from the backing vocals …

IMO parts of the backing-vocals are just vocalizations, not words.