Editing on Garageband – DBS Students Week 4
This website from Berkley [http://multimedia.journalism.berkeley.edu/tutorials/garageband-basic-editing/] is an excellent simple step by step introduction to editing speech on Garageband.
These two YouTube videos are useful, too.
“GarageBand Tutorial 1: Edit an Audio File”
And “Editing Audio Files in GarageBand” is pretty good