I have a file imported, but it has music in it and I don’t want the music. I have a separate file of the music and I’d like to use destructive interference to surgically remove the music from the clip. However this requires the music to be perfectly aligned, and have perfectly correct amplitude. I’ve tried the noise removing tool but that damages the main audio far too much, as well as removing SFX that aren’t part of the music. Is there a tool or alternate application I can use?
This is irrelevant, but I am using Ubuntu 20.04.1 LTS, Audacity 2.3.3 (but if I need to switch versions it won’t be a problem), installed from my distribution’s release
That’s the tough part. It’s not only the amplitude that must be correct. Every sample must align perfectly, and that is often impossible to achieve.
Demonstration that the theory works:
Generate a 440 Hz Tone (Generate menu > Tone)
Generate a 1234 Hz tone in a new track.
Select both tracks and Normalize to -8 dB (Effect menu > Normalize)
Select the second track and duplicate it (“Ctrl + D”)
Select the first and second tracks, then “Tracks menu > Mix > Mix and Render”
You now have 2 tracks. One contains a 1234 Hz tone, and the other contains a mix of two tones.
Select the “1234 Hz tone” track and apply “Effect menu > Invert”
The 1234 Hz track is now the inverse (180 degrees out of phase) with the 1234 Hz component in the “Mix” track.
Select All (“Ctrl + A”)
“Tracks menu > Mix > Mix and Render”
The result should be a perfect 440 Hz tone - the 1234 Hz tone has been cancelled out by destructive interference.
In the above demonstration, it’s the final three steps that produce the “cancelling out” effect.
In your case, you need to match the amplitude and perfectly align the two tracks. Then you need to invert the music track, and mix the two tracks together.
My bet is that it won’t work very well due to tiny differences between the music in the two tracks.