With a dog that exhibits fear like this, I would not recommend being stern. That could just compound the problem when the dog starts to associate the loud scary noises with his human suddenly becoming unpredictable. While Cesar Milan's methods may work with some dogs, his general rule of thought is that every single behavior is dominance motivated. IMO this is baloney - most behaviors have nothing to do with dominance.
Livin in a Newfie Drool Zone