In a tumultuous period for the audio industry, with millions of active shows swirling ever-changing platforms and business models, “Radiolab” has managed to stay above the fray. Its listening has remained constant since the host transition, Dagher said. And it is the rare podcast still capable of generating something like a broadly shared listening experience, as it did with a show last year about the hidden life of Helen Keller, or a series from the year before tracing the cultural history of cassette tapes. Among Miller and Nasser’s ambitions are extending that legacy for another two decades. Almost in unison, they described their most sacred duty to the show in three words: “Don’t break it!” Under Abumrad, in partnership with his longtime foil and co-host, Robert Krulwich (who helped define the show in 2005 and retired in 2020), and the original executive producer, Ellen Horne (who left in 2015), “Radiolab” became a protean vessel for sound-rich, intellectually curious and emotionall y engaged storytelling. It popularized several conventions of modern podcasting, including layered vocal tracks, cold opens (“Hey, can you hear me OK?”) and the “brain dump” episode format, in which a reporter walks a host through a story “It was revolutionary,” said Jay Allison, the founder of Transom.org and executive director of Atlantic Public Media. “We’re a sonic medium but a lot of times you wouldn’t have known it, listening to public radio. On ‘Radiolab,’ every second was built completely for the ears, considered like a note in a score.” The new hosts are avowed disciplines of the “Radiolab” doctrine. Miller, 39, joined the show as an intern in 2005 and later became its fourth staff member. She had been working as a woodworker’s assistant in Brooklyn when she was hooked by an episode on the science of emergence, in which a segment about synchronized swarms of Southeast Asian fireflies integrated an ethereal descores: ripples of the lake, the song of the birds. “It was like nothing I’d ever heard before,” she said. “I was like, What is that? I want to get inside of that.” Nasser, 37, wrote a cold pitch to the show in 2010 After hearing an episode about an epidemic of laughter in Tanganyika (now Tanzania), the subject of his doctoral dissertation at Harvard.