In Lush's previous incarnation authors were able to simply upload audio stories to the site, but currently there's no way to do so. Instead, authors have to create an outside download/streaming link for their audio, post it in the 'Self-Promotion and Marketing' forum and then post a link to that post along with the text version of their story.
People love audio stories and this is a ridiculously clunky way to bring them to Lush. One of the admins (Thanks, Clydia) has told me that the technical crew is fairly small and is working on other upgrades to the site. Nevertheless I urge all audio creators and fans of audio stories to contact the site and request that this be made a priority.