Audio first, animation second

Audio was first, image second, for most of these pieces.
Oskar Fischinger (father of "visual music," or the music animation, 1920s, 30s, 40s) worked with a composer to create some of his "motion paintings."

Studie nr 8 (excerpt) by Oskar Fischinger from CVM on Vimeo.

Signe Baumane's wonderful "Teat Beat of Sex" animations (sex from a woman's point of view):

"Teat Beat of Sex" from Signe Baumane on Vimeo.

Other animations made from audio interviews:

Storycorps (National Public Radio's audio interview program)

Nick Park's "Creature Comforts"