Audio has been around since, I suppose, the spoken language. The difference now is distribution and availability. Audiobooks, podcasts, smart phones, voice controlled home speaker systems, connected cars, and who knows what will come next.
StoryOrigin is such a feature-rich source for authors and now there's support for audiobook reviews, too. Here's the video version just for kicks: https://youtu.be/iCoNIiSDW8k...
The ultimate in content repurposing.
Gone are the days when a publisher could take out an ad, count on a few reviews, and have an author do a couple...