I work for a health insurance company negotiating the rates we pay hospitals and doctors. Many moons ago I worked as a casino dealer, which definitely helped with the stutter. I was forced to talk out loud and in front strangers. At first the worst was dealing craps because it's a very vocal game. You have to call the dice, solicit bets, and repeat the bets when the player makes a bet so the boxman/floor person can hear it and so on.