After adding 15 hours of free audiobooks listening to its subscription plan late last year, Spotify today is introducing a $9.99 per month option that will allow its free users to also access its audiobooks collection. The company announced on Friday its new “Audiobooks Access Tier,” which, similar to the service offered to subscribers, allows customers in the U.S. to stream 15 hours of listening from its catalog of over 200,000 titles. With the addition, free Spotify users will able to continue...