I met my doppelganger late one evening in March, when he began posting odd comments on my Facebook page. "Happy to know you, sir, and to know more about humor, that zany engine that propels me through life," he wrote on my timeline. He followed up with an instant message asking me how to pronounce certain words in Swahili.

His name is Peter Berkrot, and he was the audiobook narrator assigned to read a book I co-authored called The Humor Code: A Global Search for What Makes Things Funny. At the time, he was doing some preparatory research before the recording and had some questions about the Swahili terms we'd used in a chapter about a trip my co-author and I took to Tanzania.

Berkrot, I soon learned, is likely best known for playing Angie D'Annunzio, the caddy in the 1980 comedy Caddyshack who was on the receiving end of Bill Murray's insane Dalai Lama speech. I was thrilled that someone from one of my favorite movies would be channeling me in an audiobook, but felt guilty about referring to Berkrot as "That guy from Caddyshack" when discussing it with others. The 55-year-old Berkrot, however, seems fine with being known for a role he played 36 years ago. "I struck gold early," he says. "Then went back to digging like everyone else."

For Berkrot, "digging" meant struggling for decades as an actor—scoring a handful of film and TV roles, performing in and directing regional theater productions, doing television voiceover gigs, and working as an acting coach. Work was touch and go, he says, until 2009 when he started narrating audiobooks. Since then, book narration has essentially become his full-time job. He's read more than 170 audiobooks and is averaging four a month for a variety of publishers, each typically paying between $2,000 and $3,000. He's even been nominated for an Audie award, the industry's version of the Oscars.

"At age 50, I finally started to make a living," says Berkrot. "It's the first time I've seen technology not be a parasite, but actually help the arts."

He's referring to the digital audiobooks. Audiobooks have become a billion-dollar industry, with the number published nearly doubling each year—due largely to digital downloads. "It's been a very exciting and breathless few years," says Michele Cobb, president of the Audio Publishers Association. "Audible and the iPod helped to grow the industry immensely. Now, with a smartphone, you can carry your audiobook wherever you go."

In other words, digital audiobooks have become part of the modern multitasking lifestyle. People are listening to audiobooks as they run, tidy the house, or just go about their daily lives, as opposed to simply stockpiling of audiobook CDs for long drives. That means there's more work than ever for audiobook narrators. (An audiobook-narration school, the Deyan Institute of Voice Artistry and Technology, even opened in Los Angeles in March for those eager to break into the business.)

>Gone are the "halcyon days" of folks shelling out for a dozen audiobook cassette tapes. Instead, most listeners pay $15 a month for Audible.

The growing workload is good news for Berkrot, since, as he jokes from his home in Gloucester, Massachusetts, "I am morbidly obsessed with the sound of my own voice." But, he adds, there are ups and downs to being an audiobook narrator. While people are buying more audiobooks than ever before, he says, they're spending less per book. Gone, he says, are the "halcyon days" of folks shelling out $50 or more for a dozen Harry Potter and the Goblet of Fire cassette tapes; instead, most listeners pay $15 monthly for a book a month from Audible. That means there's less money for production costs, which means many audiobooks aren't recorded in professional studios anymore. Instead, most narrators like Berkrot hire sound engineers and work from small home studios. Those studios are, however, easier to run thanks to cheaper recording equipment and editing programs.

"It's changed how many books are now produced," Cobb says. "People can now do it in an easier environment. You can do it in your pajamas."

Audiobook directors, once a common feature, also are increasingly uncommon. Berkrot often is his own director, prepping and shaping each narration—a feat achieved by reading each book cover to cover and developing the vocal qualities of each character. Since The Humor Code is nonfiction, he tells me he didn't have to bother developing the dozens or even hundreds of characters that can appear in some epic novels, but he still had to settle on my voice as the narrator. After some thought, he settled on a somewhat playful young voice. "Unlike some reporting on science, it's not dry," he says. "Obviously, you had a good sense of humor." In other words, I came across as a bit of a goofball—which, judging from the sort of stuff he's been posting on my Facebook page, made Berkrot my perfect audio doppelganger.

Berkrot can record about a hundred pages a day, so he narrated our 256-page book in about three days. Berkrot uses an iPad, soundlessly scrolling through a PDF of the book so he needn't worry about removing the sound of flipping pages, as narrators did in the past. But he and his engineer still must "punch and roll"—rolling back the recording and beginning anew each time he makes a mistake, something that typically happens about three times a page. The longest he's ever gone without a flub is 13 minutes.

That's surely a much better track record than that of those Berkrot considers interlopers in the audiobook business: authors who read their own books simply for the money or ego boost. While he thinks some writers, like Neil Gaiman, do a great job narrating their own books, he says that "when most authors read their books, it sounds like they're simply reading." Berkrot insists that what he and his fellow narrators do isn't reading at all. "You're immersing yourself in the story," he says. "If you're doing it right, you are really thinking about entering that world. I've cried more than dozen times while narrating a book."

That's why Berkrot is unabashedly enthusiastic about his audiobook work, maybe more than anything in his career since Caddyshack. "I love it," he gushes. "I am making a living making literature."

"Well, some of it is crap," he adds, "but some of it is literature."