I'm generally a fan of the believability of The Walking Dead universe, but whoever decided that decapitated zombie heads should still make raspy sounds sure screwed up.
Discussion
Zombie apocalypse may not look the way it is pictured in the movies, but being ready for it is never a bad idea.
They did this for the same reason Star Wars has laser gun and explosion sounds in space.
Zombie teeth would have fallen out of rotting gums within a month after death.
Followed #plebchain
Best to have left it to teeth gnashing/grinding sounds. Could also have thrown in some tongue clicking
Are they like snakes? Removing the head of the snake does condemn it to die, but it ain’t exactly a quick process. The head is still very much alive and dangerous for many minutes.