Who's voice is that?

With your sound clip loaded, go to Effects, then Pitch, and then pick Shift. Lower the value of the sound to whatever you like, and make sure to click the "Preserve Duration" box. Below that is the Mode settings, click on the arrow and find one that you like from the list.

That should take care of the pitch. Then, try adding a phaser or Flange or Chorus to the voice lightly to give it an otherwoulrdly sound. Also, some reversed reverb would be good too, and is easy to do. ALso, you might want to try mixing two sets of altered voices together. Take the orignal clip before you lower it, and copy it all to a new window. Now lower one voice, then lower the other to either 3 semitones above of 3 semitones below it. Mix them together each the same volume. This turns the original sound into a kind of dual toneality, and also, you have put the sounds together to form a musical Minor.