Minus one is a common term used to describe soundtracks and audio files used for karaoke in which the vocal track is absent, leaving only the instrumental backing. The vocals on MP3s by popular artists can be partially muted to suit this purpose using common audio-editing software.

Software

Almost any audio-editing software can be used to mute -- but not eliminate -- vocals on a prerecorded stereo audio file such as an MP3 or WAV.

Technique

The process for removing vocals varies from program to program but always involves converting a single stereo file split into two separate mono files. One is then inverted, and then the two are combined again into a single stereo file.

Formats

The edited file can be saved as a WAV or MP3 and burned to a CD. WAVs offer higher fidelity, but the files are much bigger. An MP3's sound quality will be slightly lower, but you will be able to fit many more songs on a CD.