You can edit loads of stuff on this program i found!
Nasality, Pitch and even Hoarseness. Also you can change the gender from male to female to child and vice versa. It's easy to use. The only downside is the price, but once thats obtained you can theoretically voice your own series without any problems!
You dont even need to put on a high pitched voice. Just do your normal voice, let it analyze your tone and you can totally change your voice!
The program is called: Vocal Transformation Professional and is avaliable from http://www.e-vir.com/
Details off the site: "Vocal Transformation is a software module that allows transformation of vocal signals by manually changing of defined voice pitch and vocal tract values with high performance quality. This powerful tool is based on robust algorithms that provide flexible process of vocal file and let the user to save and play the transformed file."
The 7 day trial version is avaliable and doesnt allow saving of files by using the export function. Importing works fine though, because i can use my sound recorder to make the file with my microphone.
Also you can take wavs from the internet: eg, homer simpson/ morpheus and change the pitch and stuff! you can make homer sound like a teenager and morpheus sound like someone with a cold!
Hillarious stuff thats a must buy for anyone who plans to include a large variety of vocals!