WATERLOO - The digital revolution has reached the Waterloo Public Library.

The library began offering electronic audio books, or e-audio books, earlier this month through the Web site www.netlibrary.com, which allows patrons to download books to their mp3 players or computers.

Librarian Sheryl Groskurth said the service will take advantage of the popularity of digital music players and allow people to download books anywhere and at any time.

"People can do it 24 hours a day. You can just get on a computer and download your books. It just seems a lot simpler to do it that way," she said.

The service does have limitations, however. It is only compatible with Windows Media Player, which means the iPod, the market leader in digital music players, will not work with the service. A list of compatible players is available at the library's Web site, www.waterloopubliclibrary.org

In addition, the library's subscription to NetLibrary will not carry the latest best-selling novels, like Dan Brown's "The Da Vinci Code" or any Michael Crichton novels. Groskurth said services that provide those titles are too expensive, costing more than 10 times as much as the service the library pays for.

But NetLibrary has plenty of titles to choose from, including Dan Brown's prequel to the "Da Vinci Code," "Angels and Demons," she said. More than 950 books are available in nearly every category, including self-help, romance and mysteries.

Its collection of classic books, like "The Adventures of Huckleberry Finn" or "The Adventures of Tom Sawyer," should please book report procrastinators, Groskurth said.

"I was glad to see (classic books), because we get kids' moms coming in here looking for Huck Finn three days before a book report is due," she said.

To use the service, a person needs to have an account with the library and set one up with NetLibrary. An account with the online provider can be opened by logging onto the Web site from the library or by calling the library.

Once the file, usually about 150 megabytes in size, is downloaded to a computer or digital music player, it will automatically expire in three weeks. It can be renewed once, though it's possible to download it a second time after it expires. Up to 10 downloaded books are allowed at one time.

Henry Epperson listens to three or four audio books a week during his 40 minute round-trip commute, and while correcting papers for his behavioral disorder class at Cedar Heights Elementary. He listens to so many books he now picks them out at random. On this day, "Entombed" by Linda Fairstein is at the top of his audio book stack.

"You don't have to listen to it if you don't like it," he said.

He hadn't heard of the library's e-audio books yet, but said if he ever buys an mp3 player he would use the service to avoid late fees.

"I always have trouble getting here to return them," he said.

The decision to offer the service was an easy one, Groskurth said. Audio CDs are the most popular item at the library, and the e-audio books service has proved popular at other libraries.

The proliferation of mp3 players and the convenience of downloading audio books have made e-audio books a hot market, said Mary Beth Roche, president of the Audio Publishers Association.

"A truly explosive area is the growth of downloads," she said. "One of the exciting things about this is that it is bringing new customers."

According to www.audible.com, which sells e-audio books, 50 percent of its first-time customers have never listened to audio books, she said.

The format is so popular even librarians are shunning traditional books for the newer format. Groskurth said the only way she consumes books now is by listening to them, usually on her one gigabyte SanDisk mp3 player.

"I never thought I'd own one of these (players)," she said. "It was kind of scary at first, but I love it."

Contact Jens Manuel Krogstad at (319) 291-1580 or jens.krogstad@wcfcourier.com.