how do people isolate specific audio tracks from a file without access to the master tapes? Such as when someone makes an isolated vocal or bass track of a song or when someone makes a mashup of instruments from one song with the vocals from another.

Question

Such as when people make “isolated bass/vocal,” tracks of popular songs or make a meme mashup of one song with he vocal line of another over it?

In: Technology

Answer 1

Not commenting on isolating individual instruments, but a common trick to remove the voice for a karaoke track is to subtract left from right channel. In most stereo recordings, the voice is present with equal intensity in both channels.
This is how cheap karaoke machines work.