Pitch manipulation of Audio recorded Sounds

I have a challenging task

Task:

Just say something into your iPhone or capture a friend saying something. Then application make it sound even MORE ridiculous with your choice of over a dozen different voices. Voices of animals, guitar, drum etc. In this task we have to convert Pitch Manipul开发者_Go百科ation I suppose.

The easiest way to change the pitch would be to speed it up or slow it down (half speed = down one octave, 2x speed = up one octave). But there are algorithms for maintaining speed...

http://www.dspdimension.com/admin/time-pitch-overview/

http://users.ecel.ufl.edu/~cdeng/pitch_shifting_algorithm.htm

Pitch shifting is already been discussed here

Real-time Pitch Shifting on the iPhone

You will have to add animal, guitar, drum sounds to the output stream for extra effects.