A function to automate setting shape keys for a mouth on a mesh in Blender.

chat.py

import bpy
import random

def chat(speech, speed):
    slist = list(speech)
    mouth = bpy.data.objects['Mouth']
    face = bpy.data.objects['Face']
    f = 1
    for x in slist:
        if (x=="a") or (x=="e") or (x=="i") or (x=="o") or (x=="u") or (x=="y"):
            mouth.select = True
            bpy.data.shape_keys["Key.001"].key_blocks["Oh"].value = 1
            mouth.data.shape_keys.key_blocks["Oh"].keyframe_insert("value",frame=f)
            mouth.select = False
            face.select = True
            bpy.data.shape_keys["Key.002"].key_blocks["Chin"].value = 0
            face.data.shape_keys.key_blocks["Chin"].keyframe_insert("value",frame=f)
            face.select = False
            f+=speed
        else:
            mouth.select = True
            bpy.data.shape_keys["Key.001"].key_blocks["Oh"].value = 0
            mouth.data.shape_keys.key_blocks["Oh"].keyframe_insert("value",frame=f)
            mouth.select = False
            face.select = True
            bpy.data.shape_keys["Key.002"].key_blocks["Chin"].value = 1
            face.data.shape_keys.key_blocks["Chin"].keyframe_insert("value",frame=f)
            face.select = False
            f+=speed

song = "heeello  my  daaaarliiiing     heeello my hooonyyy     heeello myyy raaagtiiimm gaaaaal"            
chat(song, 3)