One thing I could suggest, so that you bring the enormity of the animation down to something you can work with, is to break the sound file into separate pieces, animate them as separate files, then bring them all together in a video editor. 6 minutes is a long animation, and smaller chunks would make the process easier on you.

I suggest breaking the sound file into 1 minute (or wherever there is a pause in the dialog) sections and work from there.

EDIT: this will also allow you to change camera angles, add transitions, or focus in on facial expressions or body parts (like the eyes), and give your animation a bit more life.

If I had a nickle for ever time a woman told me to get lost, I could buy Manhattan.