Booktrack, an e-publishing venture offering publishers the ability to add customizable soundtracks to digital titles, has secured $5 million in funding led by investments from COENT Venture Partners and Sparkbox Ventures.

The new round of funding comes on the heels of $3 million in financing raised by Booktrack last year. The company plans to use the new funding to support recent overall growth, acquire more book content and support direct to consumer sales of Booktrack titles via its e-book store.

Booktrack CEO Paul Cameron said, “our vision has always been to advance digital publishing and content to connect readers with an exciting and modern may to experience and e-book with a soundtrack.” The company has about 50 publishing deals and offers about 15,000 titles. Cameron claims Booktrack has attracted more than 2.5 million readers to its site, currently the only place where consumers can buy a Booktrack title.

The list price of a Booktrack title includes the e-book price plus a separate fee for the soundtrack, though the consumer only sees the full list price. Publishers get 70% of the e-book price, Booktrack gets 70% of the soundtrack fee.

Booktrack will create a polished soundtrack for a title for a fee of about $1,000 or publishers can add their own. Booktrack works with publishers to create movie-style soundtracks that include licensed music as well as sound effects, effectively turning e-books into radio plays with rich musical scores. Cameron said that while enhanced e-books have not sold well, adding a soundtrack is different since it doesn't force readers to leave the text. Cameron said the idea for Booktrack came from watching bus and train commuters read print books while listening to music on portable devices. “Why listen to music unconnected to the book you’re reading?” he said.

After launching in the early 2000s, Booktrack went dark for about 18 months while it reworked its technology. The debut of the iPad “changed everything,” Cameron said, making it easier to add music and sound effects to books in addition to being able to synchronize the sound/music to the reader’s individual pace of reading. Booktrack also offers tools that allow big publishers or self-publishers to create their own soundtracks out of a library of more than 20,000 licensed audio files.

Booktrack offers music as well as sound effects (from gun shots and footsteps to explosions and water splashes). Music is tagged for emotional qualities and the platform allows you mix the sounds, synch specific sounds to specific passages or words and then publish the sound enhanced e-book privately or publicly.

Cameron said the company also markets its technology to teachers and students—the firm claims e-book soundtracks helps lesson retention—and that more than 12,000 schools around the world use it. Students and other consumers can create personal soundtracks for free.

“It’s good for backlist titles, you can add sound to famous public domain books or blockbuster titles and we’ve attracted a lot of users without having all the biggest books” Cameron said. “Booktrack offers an enhanced experience delivered while you read.”