On a blazing Sunday afternoon, the interior of downtown's Union Station provides a cool refuge from an early-September heat wave. But on this particular day, cool takes on its other meaning as, amid the bustle of arriving and departing passengers and the muttering of the odd street person, a haunting soprano aria echoes from somewhere in the station's old ticketing hall.

A puzzled teenager pauses long enough to conclude to his mother, “Oh, they're shooting a movie.” A logical assumption — this is Los Angeles, after all.

The remark provokes a smile from Yuval Sharon, the maverick founder and artistic director of the Industry, a 3-year-old, upstart experimental opera company.

Sharon and a handful of technicians and singers are in the midst of testing a wireless sound system for the Industry's groundbreaking, site-specific sophomore production: Christopher Cerrone's Invisible Cities, which Sharon is calling L.A.'s first “headphone opera.”

What that means exactly is something that even Sharon won't be able to say with much certainty until the opera opens on Oct. 19. But it does include eight singers, seven dancers (from L.A. Dance Project), an 11-piece chamber orchestra, about 200 audience members in Sennheiser wireless headphones and a lot of bewildered passers-by.

The show will begin with a prelude with the orchestra in the art deco Harvey House room. Then the audience members are released into the station and grounds to wander freely and discover the performance for themselves before reconvening for the finale.

Sharon says he's hoping that “audience members might think that [the singers and dancers are] normal people waiting for a train or staying at Union Station or whatnot. And then, only when things become more and more extraordinary, that you realize they're carrying on this kind of secret drama.”

Invisible Cities is the follow-up to the Industry's brash, 2012 inaugural show, Anne LeBaron's “hyperopera” Crescent City. That show also mixed performers with audience members, who could walk the perimeter of the art installation–like set during the show, albeit in the controlled environs of an Atwater Crossing warehouse.

“I think so much of what Crescent City was about,” reflects Sharon, who also directed that production, “was this multiplicity of perspectives that actually became content, as well as the form of that piece. And I wanted to follow with those ideas and take them to another level.”

“Another level” is putting it mildly. The immersion of an audience wearing headphones and watching live performers in an active train station is a blending of public space and extreme subjectivity that breaks from traditional, big-box opera.

“That's what I think is the pleasure,” Sharon continues, “which is the idea of setting it in a space that has its own rhythm, that has its own life, that doesn't necessarily have the same idea of a spotlight … the beautiful and the tacky and the ordinary all in this one space.”

Immersive theater is hardly unprecedented, and neither, for that matter, is headphone opera. Sharon says he found inspiration both in Sleep No More, the London stage company Punchdrunk's twist on Macbeth, in which audience members encounter characters while wandering the rooms of a Manhattan warehouse, as well as in London's Silent Opera, which performs traditional opera in nontraditional places to a seated audience listening to the score through headphones.

Sharon says the real credit for a headphone opera that moves freely throughout a public building belongs to the show's sound designer, E. Martin Gimenez.

Gimenez says the idea came to him while working with L.A. theater company Poor Dog Group at the Getty Villa several years ago. “I was walking around and I saw that [the museum] had an audio tour system,” he recalls. “And I was thinking, 'Oh, this would be a very interesting thing for us to utilize.' I was thinking about that for another [piece], but Yuval went, like, 'That's great. But let's do it on a grander scale.' ”

What clicked for Sharon was the combination of headphones and Union Station as a joint solution to a show that had been nagging him since 2009: Invisible Cities, which he had directed that year in a more traditional but problematic workshop staging at VOX, New York City Opera's new-works laboratory.

“I thought it was incredibly beautiful, and I thought it really challenged our traditional ideas of dramaturgy and operatic structure and all that kind of stuff,” Sharon remembers. “[But] Chris really writes at extremes at that quiet register, and he loves dealing with the idea of sonic resonances and the decay of sounds and all of these things that don't necessarily play in a traditional theater.”

Invisible Cities fits with Union Station for another reason. Its libretto was adapted by Cerrone from Italo Calvino's elliptical, quasimystical 1972 experimental novel of the same name. The book depicts a young Marco Polo regaling Kublai Khan with descriptions of 55 fantastical cities, which the Italian claims to have encountered on his journeys through the khan's empire.

The cities are literally impossible places, imaginary horizons of thought, and Polo's descriptions read like poetic koans grappling with the fundamental yearnings, regrets and paradoxes of existence. Like the city of the dead, Adelma (they're all named after women), where everyone we've ever lost in our lives is reborn but as fishmongers or as grocers, and as people who no longer recognize us.

“It's such a poetic idea of Calvino's to look at these elemental, existential problems and to make them geography,” Sharon says, and an equally poetic idea to set the adaptation at a transportation hub that leads to various cities.

But it's one thing to say “headphone opera in Union Station” and another matter entirely to put one on. Sharon says it took a year of intense negotiations with Metro just to get the transportation authority's nod. “Now they're very cooperative and very excited,” he adds.

Equally daunting have been the technical hurdles. Gimenez says the production is stretching the ability of a consumer wireless headphone system intended for a suburban den. That stretch includes an industrial-grade transmitter and stringing a small forest of commercial antennae around the station.

The results could be startling. A test drive of the Sennheisers with sopranos Delaram Kamareh and Ashley Knight performing to a recorded test track of the musicians (during the show, the musicians will be live in the Harvey House room) revealed a clarity and sense of spatial depth that produced the uncanny sensation of a singer standing just behind the listener, singing gently into his left ear.

Sharon, who assisted Achim Freyer on Los Angeles Opera's 2010 Ring Cycle and spent four years as project director of VOX, admits that the production is a gamble for the young company.

“It's a risk unlike any I've ever taken before,” he says. “There are so many unknowns.”

It's not unlike the city Irene from Calvino's novel, he muses. “You know the name of the city, and it's far off, and you keep walking closer and closer and closer to it, and it always stays far away.

“And in a way,” he adds, “that's a good metaphor for this entire creative process. Because you have this image of what you want to do, and it's a vision. And you just keep walking toward it and walking toward it and walking toward it. And you have this limited time to get as close to that vision as you possibly can. To that city.”

INVISIBLE CITIES | The Industry, at Union Station | 800 N. Alameda St., dwntwn. | Oct. 19–Nov. 8 | invisiblecitiesopera.com

Correction: The original version of this story had the wrong name for the composer of Crescent City. The correct name is Anne LeBaron.

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