Phase Cancellation During Recording

Graham Cochrane put up an excellent video explanation of dealing with phase-cancellation during recording. If you’re not familiar, this is a phenomenon that occurs when you record the same source with two or more mics. Sound is made of waves that push and pull air. When those pressure differences hit our ear drum, we perceive them as sound. When they hit a microphone, they’re converted to electrical signals that we can record. When you combine multiple versions of the same material, the peaks and valleys may be out of sync, which will actually reduce the volume of the sound and make it sound weak.

 Inverted Phase

Inverted Phase

Take a look at the close-up from Graham’s video showing the two guitar tracks. You can see that, for the same time-slice (the highlighted section), the upper track’s wave form is going down, while the lower wave’s form is going up. When played together, these two sounds cancel each other and make the resulting sound weak and thin.

The fix is to invert the phase of one of the tracks. This is a pretty well-known solution, so that’s not what’s so great about the video. What makes it worth watching is the audio demonstration of what phase-cancellation sounds like. Once  you hear it, you should be able to identify it immediately.

Graham also runs one of my favorite podcasts, the Simply Recording podcast. If you’re into recording at all, you should definitely check it out.

Via The Loop.