Every musical biopic eventually reaches the same moment: the actor steps up to the microphone, and the film has to decide whose voice comes out. For nearly a century the genre has answered in three ways — borrow the real singer’s recordings, blend them with the actor’s, or let the actor sing live — and each answer says more about its era than any period wig. It is also why a genre routinely dismissed as formula keeps delivering some of Hollywood’s biggest hits.

A musical biopic dramatizes the life of a real musician and uses their songs as the story’s spine. Its origin myth is The Jazz Singer, the Warner Bros. landmark generally credited as the first feature with synchronized dialogue, in which Al Jolson sings and then speaks the line “You ain’t heard nothin’ yet.” Strictly speaking it is not a biopic: Samson Raphaelson wrote the story behind it after watching Jolson on stage, and Warner advertised the picture as a biography of its star, whose cantor father had opposed his show-business career.

The genre proper began when Hollywood turned that life into an actual film. In The Jolson Story (1946), Columbia cast Larry Parks as the singer while Jolson’s own voice supplied the songs; Parks earned a Best Actor nomination for a performance built around another man’s recordings. The studio-era template had already been fixed by Yankee Doodle Dandy (1942), which won James Cagney the Best Actor Oscar as George M. Cohan: humble beginnings, a breakthrough, a crisis, a triumphant last number.

The borrowed-voice method never went away. Jamie Foxx won Best Actor for Ray performing to Ray Charles’s own recordings, and Marion Cotillard won Best Actress for La Vie en Rose miming to Édith Piaf’s records and to those of singer Jil Aigrot. But prestige increasingly attached to actors who sang for themselves. Sissy Spacek won the Oscar for Coal Miner’s Daughter using her own voice as Loretta Lynn; Joaquin Phoenix and Reese Witherspoon sang as Johnny Cash and June Carter in Walk the Line, which won Witherspoon Best Actress; and Timothée Chalamet played guitar, harmonica and vocals live on set as Bob Dylan in A Complete Unknown, which drew eight Oscar nominations.

The blockbuster era settled on a blend. Rami Malek’s Freddie Mercury in Bohemian Rhapsody mixes Malek’s vocals with Mercury’s master tapes and the voice of singer Marc Martel — “an amalgamation of a few voices,” as Malek put it — and the film grossed more than $900 million worldwide. That model only works with the music rights in hand, which is why the musician or the estate so often sits inside the production: Queen’s Brian May and Roger Taylor on Bohemian Rhapsody, Elton John as an executive producer of Rocketman.

The commercial stakes have never been higher. Michael, Antoine Fuqua’s film starring Michael Jackson’s nephew Jaafar Jackson, crossed $1 billion worldwide this summer, overtaking Bohemian Rhapsody as the top-grossing music biopic and passing Oppenheimer as the highest-grossing biopic of any kind.

Next comes the boldest version of the old bargain: Sam Mendes’s Beatles project, four films each told from one band member’s point of view, all due in cinemas in April 2028, with Apple Corps and the surviving Beatles granting full life-story and music rights. Almost a century after Jolson’s first spoken line, the genre’s oldest question now has four voices to answer for.