Self-published authors have figured out they can maximize the earnings of their book by producing both a POD paperback version as well as an ebook version, usually Kindle at the very least.
Many of us may be "leaving money on the table" by not offering an audio version as well. Just as Amazon entered the print-on-demand business with CreateSpace, Amazon also owns Audible.com, or acx.com.
This company allows authors to produce an audio version of their ebook or print edition. Once the audio version has been created and uploaded to Audible.com, the audio version of the book will automatically be linked to the Kindle and paper version's listing on Amazon.
The audio book will be distributed to Audible.com, Amazon.com and iTunes if the author grants exclusive distributor rights to acx.com.
When I began investigating Audible.com, I first thought this would be another endless task I had to learn how to perform. A little research indicated this is something I need to consider and make a decision about quickly.
It appears more and more people are using audiobooks yet only 5% of all published print and ebooks are ever converted into audiobooks. I like the idea of increasing demand combined with low competition!
So take a look at acx.com and see if this is a business option you need to act on.