Can not say I have seen anyone use audience schema from http://schema.org, maybe @danbri could point you to some examples in the wild
Mentions:
@glennjones @danbri I found one on IMDB #feelsillyforaskingnow
– Dr. David Sewell on twitter
.@seoeditors @glennjones does https://www.google.com/cse/publicurl?cx=013484121852858951051:l0ojk8khoxi… help? 1 major use is http://LRMI.net education markup in http://schema.org
– Dan Brickley on twitter
@danbri @glennjones Thanks Dan
– Dr. David Sewell on twitter