Lightsabers will buzz and hum. Spaceships will whoosh and vroom. Blasters will go “pew pew.”

Star Wars: The Last Jedi is strewn with the sounds conceived and concocted 40 years ago by sound designer Ben Burtt. Now 69 and working in Lucas Valley, California, at a company named for Luke Skywalker, Burtt spends his days holed up in his dimly lit office, surrounded by movie memorabilia, mostly souvenirs of his years behind the scenes of the Star Wars films.

But his name is nowhere to be found in the credits for The Last Jedi. Like George Lucas, the Star Wars visionary who sold his company and faded from view, Burtt is both omnipresent in the new Star Wars and conspicuously absent from it.

In an August conversation, I mentioned that I had been advised to steer clear of speaking about the new movies. “You can talk about the new movies,” he said with a smile, a shrug, and then a pause. “I haven’t seen the new movies, so . . .”

Burtt’s creations—the distinctive drone of the lightsaber, the bleepity-bloops of R2-D2, and the sinister inhalations and exhalations of Darth Vader—are as essential to the soundtrack of Star Wars as the music of John Williams. By Return of the Jedi, Burtt’s pioneering work had led to the creation of Skywalker Sound, a facility that today provides sound design, mixing, and audio postproduction for multiple movie projects a year, including some of Hollywood’s biggest blockbusters. Burtt himself was also behind the sounds of the Indiana Jones movies, E.T. the Extra-Terrestrial, the 2009 and 2013 Star Trek movies, and Pixar’s Wall-E.

“He’s not afraid to get weird,” says Matthew Wood, Burtt’s protégé and supervising sound editor on The Force Awakens, Rogue One, and The Last Jedi. “He uses such strange sounds in ways that you might not ever think would work, but they do. Something’s going to stand out in the track, strangely, and you’re not going to know why, but it’s going to leave a mark.”

Burtt has a keen and excitable ear, and a habit of tuning out of conversations to tap into more interesting frequencies. He collects sounds compulsively, seeking out exotic new ones the way a lepidopterist pursues butterflies. For a recent mission, Burtt set out at dawn to acquire the heavy banging and clanging of train cars at a rail yard. Not long before that, a local man with a peculiar voice impediment caught his ear: “He’s in my logbook of five or six unusual voices in Marin that maybe I’ll find a use for some day in something.” (Burtt found the voice of E.T., Pat Welsh, in a similar way, overhearing her chain-smoker rasp in line at Seawood Photo camera shop.)

“I follow this rule that if something catches my attention, then I should capture it right then and there, even if I don’t know what I’m going to use it for,” he said. As a result, he’s got an archive of thousands of unused sounds, waiting for their moment to shine.

Behind his desk, Burtt has Ralph McQuarrie’s painting of two robots in the desert on display—the Star Wars concept artwork he glimpsed at his first meeting about the film—and a life-size model of an Imperial stormtrooper, aiming its blaster rifle at visiting guests. Elsewhere, there’s a giant Wall-E, the Dacor scuba regulator that lent the Sith Lord those asphyxial breaths, the book How to Speak Wookiee, and the ancient synthesizer that provided the voice of R2-D2 (as well as the divine thrum of the Ark of the Covenant from Raiders of the Lost Ark). “You’ve got to let it warm up and kick it a few times to get something out of it,” he said.