, which has been rapidly adding digital downloads to its vast Web store, said Thursday it had agreed to buy Audible, the largest...

Share story, which has been rapidly adding digital downloads to its vast Web store, said Thursday it had agreed to buy Audible, the largest online seller of audiobooks.

Seattle-based Amazon will pay $300 million in cash for the company, or $11.50 a share, a 23 percent premium to the stock’s closing price Wednesday.

Newark, N.J.-based Audible offers 80,000 audiobooks and spoken-word products from magazines, radio shows and newspapers. It sells its digital files through its Web site and, since 2003, through Apple’s popular iTunes service.

The deal will add Audible’s products to Amazon’s digital-media offerings, which it has rolled out the last 16 months. Customers can download movies, TV shows and music from Amazon instead of getting them in the mail.

In the past, Amazon has sent customers who wanted to download audiobooks to the Web site of Audible. The acquisition would allow it to offer digital audiobooks on its site.

The move could also allow owners of the Kindle, Amazon’s electronic book reader, to download audiobooks directly to the device. Amazon introduced the Kindle to great fanfare late last year.

“The fact that the bottom of the Kindle has volume controls has always thrown me off,” said Evan Schnittman, vice president for business development and rights at Oxford University Press.

“But now there is a real coordination here that is clicking all of a sudden. This is just another step in making the Kindle a more universal product,” Schnittman said.

Steven Kessel, Amazon’s senior vice president for worldwide digital media, would not comment on how Amazon would use Audible or integrate audiobooks into its products.

“We think that Audible for many years has been providing the best customer experience in the spoken-word space,” he said. “Now being able to have that as part of the Amazon family is what gets us excited.”

Audible content is featured prominently on Apple’s iTunes, and Apple and Amazon are fiercely competing in digital-media downloads.

But the buyout won’t affect Audible’s agreement with Apple, which is to expire in late 2010, Audible Chief Executive Donald Katz told The Associated Press. Apple did not respond to a request for comment on the deal.

The audiobook market had $923 million in sales in 2006, up 6 percent from 2005, according to the Audio Publishers Association. Internet downloads were 14 percent of sales, up from 9 percent in 2005.

Amazon and Audible could try to expand the online audiobook market by loosening the content-protection software on Audible’s downloads. The software is intended to reduce illicit copying but also makes it more difficult for consumers to transfer audiobooks between computers and other devices.

Audible was one of the first creators of the software known as digital-rights management, or DRM, which consumers often complain about.

“That is going to be one of the big questions,” said Michael Gartenberg, an analyst at Jupiter Research. “Can Amazon convince book publishers to do what music labels have done and get rid of DRM on these files to make them play across the board?”

Kessel of Amazon said it was “too early to tell” whether publishers were ready to make that leap. “We’ll have to continue to listen to the customer and work with content owners in this space to provide the best experience,” he said.

Amazon stock rose 4.7 percent, or $3.49, to $77.70 Thursday. Audible stock rose 22.4 percent, or $2.09, to $11.42.

Publishers Random House and Bertelsmann invested in Audible in 2000, as did Amazon, which at the time bought 5 percent of the company.