What is mixing in audio editing?
Audio mixing is the process by which multiple sounds are combined into one or more channels. In the process, a source's volume level, frequency content, dynamics, and panoramic position are manipulated or enhanced.
What is the audio clip mixer?
The audio clip mixer doesn't control the audio tracks, but instead the audio clips within those tracks. It simply uses the tracks to identify which clip you're working with. Each audio clip mixer channel displays the results of the specific clip on that track that the playhead is over at that given time.