Create custom ringtones and alert tones in iTunes or GarageBand

You can create ringtones for your iPhone based on any music track in your iTunes library. We looked at this in depth here 

(the tutorial includes a video to walk you through the process), but to sum up: create a short, sub-30-second duplicate version of the track; convert the file type of this track from .m4a to .m4r; re-import the track to iTunes as a ringtone; sync the ringtone with your iPhone.

Better still, you can create unique custom iPhone ringtones from your own audio creations, and this is especially user-friendly if you do the creative work on the iPhone itself. Create a 30-second track in GarageBand; go to the Share options and choose Ringtone; then assign it to a contact or notification.