A vocoder basically makes a musical instrument or sound effect talk like you (or mimic whatever you use to modulate the carrier wav, your voice). Adobe Audition 1.5, my favorite editing program, comes with a vocoder in the multitrack section under effects. Here’s a vocoder video tutorial by Jason Levine. It’s part of the excellent Total Training DVD for Adobe Audition 1.5. I definitely recommend that training DVD which I think is still available on eBay. Jason uses the vocoder for the great intro clip that loads when you first launch Adobe Audition’s multitrack feature.
Anyway, here is a vocoder sample mp3 file I produced.
You’ll hear the original clips and the vocoded effect using a guitar loop. One portion has a dry voice recording saying “voice over services”. I enhanced that with the vocoded version of the same phrase on a separate track. I also added a cello wav file that I love. (The cello is probably my favorite instrument; so much emotion.) Then, I added a vocoded phrase I created with the cello as the modulating track. Very interesting sounds. I love to play with this stuff.