Kara Shallenberg and her 10-year-old son, Henry, exhausted the audiobook collection at their library in Oceanside, Calif., five years ago. With Henry's appetite for listening still strong, Shallenberg began to record herself reading his favorite books. Eventually she upgraded from a using a tape deck to burning CDs on her laptop computer. Last fall, she took her hobby to a wider audience.

Shallenberg's recordings of "The Secret Garden," "The Tale of Peter Rabbit" and other works are now available, free, to anyone with an Internet connection and basic audio software. She is part of a core group of volunteers who give their voices and spare time to LibriVox, a project that produces audiobooks of works in the public domain.

"Everything I read to Henry was copyrighted," Shallenberg said, adding that she was frustrated she couldn't share those works. "The idea of creating audiobooks that other people could enjoy was exciting."

LibriVox is the largest of several emerging collectives that offer free or inexpensive audiobooks of works whose copyrights have expired, from Plato to "The Wind in the Willows." (In the United States, this generally means anything published or registered for copyright before 1923.) The results range from solo readings done by amateurs in makeshift home studios to high-quality recordings read by actors or professional voice talent.

At its worst, a free audiobook can sound like a student reading aloud in a high school English class. At its best it can offer excellent sound quality and skilled narration infused with a passion for the text. In between is a world of competent readings, sometimes spiced with affected accents, mumbled words and distant car horns and reflecting all manner of literary interpretations.

LibriVox celebrated its one-year anniversary Aug. 10, about the same time it surpassed the 100-book mark. It also offers more than 200 recordings of short stories, plays, speeches, poems and documents such as the Magna Carta and the Declaration of Independence. By comparison the audiobook industry, which typically sells recordings for $15 to $30, released 3,430 titles, taking in $832 million, in 2004, the last year for which figures are available.

LibriVox's founder, Hugh McGuire, 32, a software developer and writer in Montreal, said 100 works are in development, all of which would be recorded, edited and uploaded by volunteers.

"The principles of the project are to be totally noncommercial, totally ad free, totally volunteer and totally public domain," he said. Readers can volunteer at the Web site, librivox.org.

What is being read

One of LibriVox's colleagues in the free audiobook realm is Telltale Weekly (telltaleweekly.org), which sells recordings for 25 cents to $8 but makes them available at no charge through its Spoken Alexandria Project (spokenalex.org) after five years or 100,000 downloads, whichever comes first. It was founded in 2004 by Alex Wilson, a writer and actor in Chapel Hill, who performs many of the readings. Another service, LiteralSystems (literalsystems.org), has 51 works available for free download and emphasizes their professional quality.

The audio format of choice for each service is MP3 (though Spoken Alexandria and LibriVox offer other options), which means the audiobooks can play on any computer and most digital music players. Unlike with commercial audiobooks, listeners are free to copy and share the recordings.

All three services rely on Project Gutenberg (gutenberg.org), the online repository of works in the public domain, for texts. Listeners often can choose from several recordings of the same work; LibriVox, for example, offers three readings of the Gettysburg Address. Among the most recorded authors are Jane Austen, Mark Twain, Herman Melville, Jack London, L. Frank Baum, Lewis Carroll, William Shakespeare and Lucy Maud Montgomery ("Anne of Green Gables").

LibriVox's volunteers, who record solo or in collaboration, are restricted in their material only to previously published works in the public domain in the United States. This open policy has let the personal preferences of readers shine through, McGuire said.

"If someone turned up with a smut book from 1850, we would do it," he said. "We did 'Fanny Hill,' which is an early erotic Victorian book. Everyone was laughing in the discussion forums about having to keep quiet while recording so their kids wouldn't hear them."

Scriptures, too

Other LibriVoxers have proposed reading the Quran (some have already read chapters of the Bible), recording Supreme Court decisions and reciting pi to an unknown, but you can assume lengthy, number of digits. A multilingual recording of the United Nations' Universal Declaration of Human Rights is under way, as is a full cast recording of "The Pirates of Penzance."

While some listeners object to the wide variety of recording quality, McGuire said, "our take on it is if you think a recording is done badly, then please do one and we'll post it as well."

LibriVox has more than 1,800 registered volunteers, and its audience continues to grow.