- Remove breaths, cough, the ringing of the phone or any other unwanted interference.
- Remove repeated dialogues.
- Add music intro/outro.
- Stretch/shorten audio and sound effects according to the length of the visual.
- Splice together audio recorded at different channels.
- Sync up different musical instruments so that they all sound on the beat.
- Loop, slice and edit beats.
You can go through these books for audio editing.