You can’t get to sleep. You’re tossing and turning. You want someone to read you a nice, wholesome bedtime story. And you want that someone to be the actor Jimmy Stewart.
The sleep and meditation app Calm has released a new story for premium users told by Mr. Stewart, the beloved actor who starred in “It’s a Wonderful Life.” But the voice in their ear lulling them to sleep is not from Mr. Stewart, who died in 1997. It is a version of his signature drawl generated by artificial intelligence.
“Well, hello. I’m James Stewart, but, well, you can call me Jimmy. Tonight I’m going to tell you a story,” the clone of Mr. Stewart’s voice begins, telling listeners to make themselves “nice and comfortable.”
“It’s a heartwarming story of love, of loss, of hope and of joy,” the voice continues. “But most of all, it’s a wonderful sleep story.”
The app is known for its “Sleep Stories” — tales read by celebrities including Idris Elba, Matthew McConaughey and Harry Styles to help users drift off to sleep. But for its Stewart story, it enlisted the help of Respeecher, a company based in Ukraine that uses A.I. to produce synthetic speech and clone voices. Respeecher said in a statement that CMG Worldwide, the company that manages Mr. Stewart’s licensing, approved the project.
Calm and CMG Worldwide did not immediately respond to a request for comment.
To revive Mr. Stewart’s voice, Respeecher fed an old recording of the actor into its system and combined it with that of a voice actor who read the new story, creating a performance in which “all the important tiny inflections are preserved,” the statement said.
Using A.I. to recreate the likenesses or voices of public figures in film, television and other content has become a contentious issue. Meta, for example, has introduced A.I.-powered characters based on celebrities like the rapper Snoop Dogg and the former N.F.L. quarterback Tom Brady that it will soon weave through its products.
Critics, however, have raised questions over the ethics and regulation of the practice. The use of A.I. by studios and entertainment companies was among the concerns at the center of strikes this year by Hollywood writers and actors.
Last month, the actor Tom Hanks and the news anchor Gayle King warned their followers on social media that their likenesses had been used in unauthorized advertisements. Cybersecurity experts have also have also cautioned that technology like “voice deep fakes” could help scammers steal from people or businesses or commit other crimes.
Mr. Stewart’s family and his estate consented to the Calm project, according to Variety, which earlier reported the story.
Respeecher, founded in 2018, has synthesized voices for 150 projects, including the football coach Vince Lombardi. It is currently working with Warner Music France, it said, on an “animated biopic” of the French artist Edith Piaf, who died in 1963, that will use A.I. to generate her likeness and voice.
The company said it did not allow its technology to be used for “deceptive uses,” including uses that would impinge on a subject’s privacy and ability to find work.
“We know voice replication technology could be dangerous in the wrong hands,” Respeecher says on its site.
“In practice, this means we will never use the voice of a private person or an actor without permission,” the site says, but adds that the company would allow “nondeceptive uses” of historical figures and politicians.