Does anyone know of any high quality voice alteration software for mac? I am looking for the type that offers excellent control over gender and one's age of voice. This would come in really handy for detective work where one needs to hide his/her identity in internet chatrooms or one-to-one voice comm thru instant messengers. I'm talking about the type whose quality is comparable to those used by FBI and other law enforcement agencies to hunt down sexual predators and such. If there aren't any available for mac, then which would you recommend for PCs?