No, it's not. Modern systems work using "statistical parametric speech synthesis", i.e., they're models trained from data. Someone did a fluffy piece about t

No, it's not. Modern systems work using "statistical parametric speech synthesis", i.e., they're models trained from data. Someone did a fluffy piece about the vocal tract modeling approach recently, but that approach sounds awful. All of the notable systems in use and all the notable research is not in that direction.