Here's the key pose that's based on the storyboard pose. Below are some breakdowns of main mouth positions created in layout. They all work within the emotion of the key pose but accent and color the dialogue.
DIALOGUE POSITIONS - LIPSYNCH IS ACTING, not merely "mouthing"
I like to design every dialogue scene based on who the character is, and how he feels at that moment. I listen to the track, close my eyes and imagine the character. Then I draw the appropriate mouths. It's a lot of fun to custom design mouths.
What I do before I design mouth shapes is write out the dialogue and figure out where the accents are. The accents are usually vowels and that is where the biggest open mouths will be.
Since this is limited animation, I plan to reuse certain mouth shapes in different orders for different words. That's why I write out the dialogue. Above the dialogue I assign which mouth shape I'm gonna use. Each mouth shape has a letter or 2 that phonetically describes the sound.This is not your normal "O" mouth, obviously. I just thought I would do something related to the key mouth shape.
"OO" mouths work best when preceded by an "O" mouth. The O provides a quick accent that helps you notice the "OO".
"I" mouths are long and tall, just like the letter itself.
"T" 's can be used for "N", "G" and some other letters.
"M" can also be used for "B" and "P", although you can make a separate mouth for each that build in intensity.
KEY