Re the comment earlier about deleting 'scratches' when you see them in you audio software - don't do this within music, especially if there are a lot - it will affect the apparent length of notes (not explaining this well but I guess you know what I mean). If the scratches are in talking or 'gaps between' it's less critical. I made the mistake of trimming out scratches once and ended up with something that sounded like a record jumping. Fortunately I still had the original and could start again. Now I just reduce the volume level of the scratch to match the surriounding (or a fraction lower).