After the shark joke, how can I raise the pitch of my tenor voice to sound like a soprano?  I want my back up chorus to sound female not male.  I belive that shifting the pitch up an octave will do the trick.  I tried the octave harmony in Izoptope's Nectar, but found a lot of artifact.  I am going to try using melodyne next.  I think I have heard of otherwise to change pitch and/or timbre to accomplish what I am after.  What ideas might you have?

ihave you tried formant in melodyne?

Trax by Flux. Pricey but it's pretty darn good. No guarantee on the artifacts but you might at least demo it first.

Earth Wind and Fire used a cool trick:
 
Record a real trumpet for the realness,... then add lots of other synth trumpets in unison. Big horn section.
 
while yearning for that option:
I would use multiple transpositions:
Clone the original track a bunch of times.
Use Sonar/Radius Transpose to move 12 steps. (experiment with settings)
    Clone, detune, add slow modulation
        Clone track: Transpose 12 steps
          Clone, detune, add slow modulation
 
Use melodyne and repeat above.
 
Use the tracks that sound pretty OK not-too-bad. The 2 octave tracks will contain interesting harmonic distortion.
 
Could also try some other semi-free transposers. Reaper has some to try: Elastique is worth testing.
 
Not doubt combining a bunch of the different programs' result will at least give you something to work with.
 
And then find a real soprano add a couple of tracks to fix the formants.
 
 
 
 
 
 
 

I've tried both Nectar and Melodyne approach. If you have a good clean take, the Nectar should work...make sure the setting for the voice is medium or high. I open up the Mel standalone and just copy/past the specific blobs and shift to whatever harmony I'm chasing. I think it's better that Nectar with less chance of artifacts. However, taking it up and octave might introduce the latter. 
 

Doing such a big shift fiddling with the formant setting is necessary.

Pitch shift and formant shift are not suppose to be the same. If you raise your voice by octave, the formant shift should be much less. In V-vocal it's like this: transpose pitch one octave up, then set Formant Control: Pitch follow=0, Shift=30~40.
 
Try to keep recording level as high as possible to avoid artefacts because V-vocal does not recognize quiet audio.
 
One more thought. To avoid extreme transposition try to record your back vocals in higher key. Let's say your tune is in A minor. Transpose the instrumental tracks to Cm or Dm and sing backing parts. That way you need to transpose them only by 6th or 5th, not the whole octave.

Castration is the only way!  

dilletant
Pitch shift and formant shift are not suppose to be the same.

That's actually the point when creating backing vocals. With the formant setting you can change the
voice so, that it's like another person singing, even when you don't change the pitch.

Nectar 2 has a good set of features that can help with that sort of thing.