When going out and shooting in the field, it's good to have multiple recordings of your sound to use as a backup in case something goes wrong. One of the most common scenarios in a real-world shoot is to have a boom mic plugged into your camera to record high-quality audio while also recording with the on-board microphone as a backup.
When importing into FCPX, all audio channels will be brought in by default. This can lead to messy sounding audio as on-board microphones sometimes offer clear sounding audio, but often pick up far more background noise than higher-quality mics.
1. Find and highlight a clip with audio channels that you wish to remove. You can turn off channels on a clip straight from the event it is contained in.
3. Scroll down to the bottom of the Inspector window and take a look at Channel Configuration. In the following screenshot, there are two stereo files attached to this video clip:
Look closely...