I received an email from Rainy in Montana (I asked her if it was.... She said that was old)
She said she can't help moving her lips when she comes to those difficult words and letter pronunciations. She asked me how i take care of that problem.
The one thing a ventriloquist should always do is interact with his dummy by nodding or disagreeing or roll his eyes anything that will distract the audience from his mouth. Unfortunately, when people go to see a ventriloquist, its like going to see a magician. Everyone tries to see how the trick is done so instead of enjoying the show, they tend to watch the ventriloquists mouth instead of the act. If you're always looking at the audience, they will watch your mouth. If you're looking at the dummy, they will watch him. DISTRACTION!!!! That is the key to successful ventriloquism.
I was taught by Paul Winchell when I was young to clench my teeth together and smile while the dummy is talking. He said always look at the dummy when he's talking look to the side at him while he is talking. There is less movement seen that way. Always make sure your figure is animated. Shifting around looking side to side turning his head etc. All this distraction takes away from the audience watching your lips. After i do demonstrations and kid classes The Adults usually tell me. I wanted to see if you moved your lips but I got caught up in the act.
There's the secret. If the dialogue and manipulation is good, No ones going to see the times you move them. And as always PRACTICE PRACTICE PRACTICE IN FRONT OF A MIRROR. The more you do that, the better you will get. Hope that helps Rainy!