The family name was Shapiro; Guidall is a permutation of his Hebrew name, Gedalyah, suggested when he was acting in a theater group touring in the Middle East in the early 1960s. He returned to school in his 50s to receive a master’s degree in social work, practicing as a therapist while continuing to act in soap operas and onstage. (He won an Obie award for his performance in the Off Broadway play “Cinders.”)

It was while doing “A Flea in Her Ear” at the Long Wharf Theater in New Haven that he heard about a fellow actor leaving rehearsal early to narrate a book, and he started doing “talking books” for the blind. “It was a gig between shows,” he said.

Most days, Mr. Guidall, 79, drives from his home in White Plains to nearby Irvington, where the owner of the Voiceworks company has outfitted his basement as a recording studio. He sits in a tiny booth lined with egg-crate-foam soundproofing, his longtime sound engineer Rich Samalin at a computer console right next to the washer and dryer.

A list of phonetic spellings for words that might be challenging to pronounce is provided, but while he read a book about Lincoln’s war secretary Edwin Stanton, who was a lawyer in Pittsburgh, the Monongahela River required a few tries. Later, an Ohio politician named Clement Vallandigham engendered paroxysms of laughter. “With a book that’s over 700 pages, the pace is important — otherwise it would take two years to listen,” Mr. Guidall said. “So I’d rather keep up the speed and go back to correct. Once in a while, I fall off the sled and roll down the hill.” (After Mr. Samalin’s splicing, no one will know.)