So you want to get that other-worldly, just arriving from the 5th dimension sound on a vocal track? Try a Reversed Reverb:
- Duplicate the track in question.
- Slice one of the vocal phrases on the new track into a separate region.
- Isolate it (remove all other region data from before and after)
- Note where the start and end points are. (this will be important later)
- Select it.
- Use the audiosuite reverse tool to reverse it.
- Now select the region and an amount about the same size after the region.
- Use an audiosuite reverb (for this example, I’m using D-Verb’s Room2 on medium setting) on the selection. (you may have to do this a couple of times to get it to sound the way you want it to).
- Now reverse it again.
- Move the region back so that it’s end time is the same as it’s original end time from above (you noted it, didn’t you?) Shift+drag will snap the end time to the grid.
- Mix with the original.
Of course, you will need to tweak the settings to taste, but those are the basics.