Scribd, which drastically cut its romance offerings this summer, continues to refine its business model. Beginning September 20, the e-book subscription service will institute a two-tiered audiobook service. Under the new model, Scribd customers, who already pay a monthly membership fee, will have access to one set of "unlimited access" titles, that will rotate. To access another set of audiobook titles, customers will have to use a monthly credit.

Scribd CEO Trip Adler, writing on the company's blog, explained that the shift will mean Scribd will feature titles marked for either unlimited access or credit-access. Subscribers will be given a free monthly credit to access the restricted title list and, when that credit has been used, will need to purchase additional access. The restricted audiobook titles will be sold at $8.99 per title.

Adler emphasized that unlimited access audiobooks “are being made available through special arrangements with publishing partners" and that the "selection will be updated monthly with new titles.”

Although Adler did not reveal the reasoning behind the change, it appears to be another effort to curb the access of audiobook listeners who are undermining the subscription model by consuming too much, which was the impetus behind Scribd's decision to reduce the number of romance titles it offers. (When Scribd announced it was cutting its romance list, it cited the difficult economics of serving an audience with voracious reading habits. In other words, romance readers were essentially cannibalizing any profits in the service by reading far more than the model can support.)

“This change will not only allow us to continue to grow our audiobook catalog in a sustainable way, but will also allow us to focus on even more content deals and offerings we know you’ll love,” Adler said.