Troubling news out of Amazon. GigaOm’s Laura Hazard Owen reports that Amazon’s Audible audiobook platform, which launched audiobook self-publishing in 2011, has announced it is now lowering the royalties it pays on audiobooks created through its “ACX” audiobook creation platform, as well as changing its “Bounty” audiobook incentive program. The ACX platform serves as a clearing house that matchmakes audiobook rights holders with producers and narrators to create a finished product.

Previously, audiobook creators who sold via Amazon received 50% to 90% royalties (depending on number of units sold) if they sold exclusively through Amazon and Audible, or 25 to 70% if they sold non-exclusively. For projects started on or after March 12, however, those rates drop to a flat 40% and 25% royalties, respectively.

Also, Audible’s “Bounty” program previously paid the creator $25 whenever their book was one of the first three downloaded by a new Audible member. Now, however, it will pay $50 when it is the first single book downloaded.

Owen notes:

The change to ACX’s royalty structure is a reminder that Amazon could also reduce its royalties on self-published Kindle books at any time. That would be a much more visible move than the changes to ACX, which the company surely realizes. But the changes at ACX shows that good introductory deals don’t always last.

Just something to think about. Given that Amazon is making noises about raising the fees on Amazon Prime in the US (and they already did raise it in the UK and Germany), they might just be starting to tighten the belt. We’ll just have to see what happens.