Mixing refers to the process of combining multiple Audacity
tracks which play simultaneously into a single track.
Audacity mixes automatically when playing or exporting, but it can also physically mix
selected multiple tracks together into one within the project. All selected tracks are mixed, regardless if the Mute or Solo buttons on any tracks are set to silence their playback.
The channel of a track being mixed affects whether it will be mixed into the left channel of the resulting track(s), the right channel, or both (mono). For example, if you have four tracks:
- Track 1: left channel
- Track 2: left channel
- Track 3: right channel
- Track 4: mono channel
and you select them all and perform a Mix and Render, you will end up with one stereo track: the left channel will contain a mix of tracks 1, 2, and 4 and the right channel will contain a mix of tracks 3 and 4.