That was a talk test for a short film called Innards, the Metaphysical Highway. Stop motion in it’s appearance, they crafted 12 different heads for Chunk all to indicate the different sounds of speech and used the Replacement Method (switching his head out between snap shots) to make his mouth appear to be changing position. 12 was possibly a few more than average, with 9 being the go to amount of Phonemes, or units of sound.
1: A, I
This ofcourse, only really applies to English speaking dialogue and may very drastically for different languages, even different accents. You don’t have to hit every sound as well, the vowels are the more noticable ones with b, m, f and l right behind, and should be held for at least two frames, assuming you’re shooting at 24/25 frames a second.(P.35 Animator’s Bible)
Japanese animations typically only have three mouth movements. Anime historian Patrick Drazen points out, there are probable historical precedents for this practise. He notes, “in the unmoving mouths of Bunraku puppets, and in Noh Theater, in which the protagonists usually wear masks, Japan as a history of giving the audience mouths that move without speaking or speech from a mouth that doesn’t move.”
Many viewers will see limitations in lip sync as reflecting low production or poor animation skills – or both.