Lawrence's QuickTip #2: Taming Vibrato in Remix Vocals

Vince Lawrence and his Slang team often find themselves either slowing down or speeding up a cappella vocal sections to match the desired tempo in their dance remixes. Here's how he deals with the ugly artifacts caused by increasing the tempo.

"You get what we call, 'the Billy Goat effect,'" he notes. "That's where the singer begins sounding like a goat because the vibrato in their voice speeds up too much when you stretch it too far to match your remix key. To counteract the effect you can fade in and out the original a cappella voices during the portions of the song where the vibrato at the same time is fading in the original vocal on a separate track. Then, fade out the original vocal while fading in the sped-up vocal to keep the cadence and timing of the vocal part together. This move takes time to feel natural with and to get sounding seamless, and you might have to fudge it around a lot to get it right, but it will sound just right when you're done."

+ Originally Posted Here
http://digitalmedia.oreilly.com/2005/10/26/vince-lawrence-slang-music.html