Actually, I’m a linguist from Prussia (in Germany, not Pennsylivania) and coincendentily I have studied this in detail. During my research I have discovered that Hollywood uses a arsinal of “speech drugs” - substances that alter speech! Tablets, injections, all Chemical stuff to modulate the voices of the actors, so that they are more becoming to the audenices. So, for instances Clooney has a voice which is several octaves higher than on the screen, he sounds like a barmaid after inhaling laughing gas. And Signorey Weiner has a raspy Bariton. Tom Cruise has a voice more in line with his pint-sized bodily built. Jennifer Aniston screetsjes like finger nails running over blackboard. Only Adam Sandler has a hallway acceptable voice, but he happens to be a jerk.