Bad teeth?

[samsonsite1]

Can we get some explanation on how to tweak the various node parameters to improve image quality and change the expression?
What do these parameters really do?

ip_audio_scale ??
use_interframe ??
expand_ratio ??
dynamic_scale ??

Also, what is the smallest size in pixels of a face can this handle?
Faces smaller than 256 x 256 are horribly pixelated. I assume Sonic is only useful for big-face talking avatars.