An experimental feature on the device, which began shipping earlier this week, allows users to have texts read to them in a digitized voice. The text-to-speech feature came under fire from the Authors Guild, which its members that Amazon might be undermining the market for audio versions of their books..

Amazon said Friday it is modifying its systems so that rights holders can decide for themselves whether they want the text-to-speech capability enabled or turned off on each title. The company has already started work on the technical changes needed to allow these settings.

"With this new level of control, publishers and authors will be able to decide for themselves whether it is in their commercial interests to leave text-to-speech enabled. We believe many will decide that it is," Amazon said in a statement.

Also in the statement, Amazon asserted that the text-to-speech feature is legal, because no copy is made, no derivative work is created and no performance is given. The company also pointed out that it is itself in the business of selling professionally narrated audiobooks through its Audible and Brilliance subsidiaries.