LOS ANGELES >> Having tried 3-D films, earsplitting sound systems and even alcohol sales in pursuit of younger moviegoers, some theater chains are now installing undulating seats, scent machines and 270-degree screens.

For an $8 premium, a Regal theater here even sprays patrons with water and pumps scents (burning rubber, gun powder) into the auditorium. Can’t cope with two hours away from your smartphone? One theater company has found success with instant on-screen messaging – the texted comments pop up next to the action.

“When I step back and think about what will get people off a couch, in a car, down the road and into a theater, the answer is not postage stamp-sized screens and old seats,” said Gerardo I. Lopez, the chief executive of AMC Entertainment, the No. 2 chain in the United States. “Why would they bother? What the hell, stay in the house.”

If Lopez sounds frustrated, he is. Ticket revenue in North America has fallen 4 percent this year compared to the same period in 2013, according to box office analysts, and attendance is equally down. The busy Thanksgiving and Christmas moviegoing periods are not expected to make up the ground.

The decline has hammered the biggest theater companies, with profit at both AMC and Regal Entertainment, the No. 1 chain, plunging more than 50 percent through the first nine months of this year, compared to the same period a year earlier.

But what really has the exhibition industry unnerved are two statistics released in the spring by the Motion Picture Association of America. Last year, despite a glut of extravagant action movies, the number of frequent moviegoers ages 18 to 24 dropped 17 percent, compared to a year earlier; the 12-to-17 age bracket dropped 13 percent.

The undiscerning young ticket buyers Hollywood has long counted on to turn out weekend after weekend are suddenly discerning. Or they are at least busying themselves with video games, living room wide-screen televisions and devices that can pull up thousands of movies with a couple of clicks. For many teenagers, the idea of focusing on a single screen for an extended stretch is anathema.

“The traditional moviegoing experience is at odds with the rest of their lives,” said Ben Carlson, president of Fizziology, a consultancy that focuses on entertainment and social media.

To combat the problem, theater chains seem increasingly open to trying just about anything. Regal, for instance, in June began offering something called 4DX in downtown Los Angeles. More than 100 seats buck and dip in close synchronization with the action on the screen. Compressed air blasts from headrests to simulate flying bullets. Fans provide a gentle wind effect.

There are two types of water effects: rain, which drops from the ceiling, and mist, which is squirted from the seat in front of you. (Patrons can turn off the water by pressing a button.)

“We’re adding to the story, not taking away from it,” said Catherine Yi, a senior editor for CJ 4Dplex, the company behind the technology. More 4DX theaters are on the way, both in the United States and abroad. Competing companies like D-Box and MediaMation are racing to roll out similar motion-seat offerings.

For many cinephiles, this is sacrilege. Even some Hollywood executives joke about bringing motion-sickness bags and raincoats.

But the target audience – men 18 to 24 – seems to enjoy it, with screenings often selling out, according to studio distribution managers. “It’s way cooler than it sounds,” said David Ramirez, 25, as he left a crowded 4DX screening of “The Hunger Games: Mockingjay Part 1” last weekend.

Newfangled multiplex ideas come and go all the time. Peter Jackson in 2012 promised to revolutionize moviegoing by exhibiting his “Hobbit: An Unexpected Journey” in a faster, hyper-realistic 48 frames per second. Ticket buyers thought otherwise. The 3-D boom of recent years has also waned.

Going back further, Smell-o-Vision and AromaRama – 1960s-era attempts by exhibitors to compete with the surging popularity of television – both quickly fizzled.

But the current move toward interactivity and immersion is unlikely to go away entirely, analysts say, in part because of a generational shift.

“You’re trying to figure out if there’s something you can offer in the theater that I would not find appealing, but my 18-year-old son might,” Amy E. Miles, Regal’s chief executive, told attendees at a gathering of movie theater owners in 2012, when some of the concepts now rolling out were first discussed.

Disney over the last two years has conducted theatrical testing of an initiative it calls Second Screen. Moviegoers were encouraged to bring iPads and use apps to play games that relate to the action in the movie. During one test, conducted during a rerelease of Tim Burton’s “The Nightmare Before Christmas,” 50 percent of the audience had iPads.

Allowing patrons to use their smartphones in certain auditoriums has been discussed intermittently by exhibitors, although worries about piracy, among other factors, have prevented that notion from moving forward in the United States. But theater chains paid keen attention to a recent texting trial in China.

At August screenings in 11 cities of “The Legend of Qin,” an animated movie, ticket buyers were allowed to log on to a Wi-Fi network and use their mobile phones to text with other attendees as the film played. The messages appeared next to the action, much like VH1’s “Pop Up Video” program.

AMC, now owned by the Dalian Wanda Group, a Chinese conglomerate, says it has no immediate plans to allow texting. But the chain is moving ahead with an enhanced experience called AMC Prime. Now operating in nine American cities with more on the way, AMC Prime theaters have ButtKicker-brand subwoofers inside reclining seats (the marketing slogan: “Get ready to feel every wow”) and 60 speakers overall, double the number in a standard AMC auditorium.

America’s third-largest chain, Cinemark, has lately experimented with theaters in four states (California, Florida, Illinois and Texas) that offer a 270-degree viewing experience. The first film to be shown in the format was the young-adult thriller “The Maze Runner.”

“Our customers really seemed to like it,” said Timothy Warner, Cinemark’s chief executive.

But Warner vowed that Cinemark would go only so far. “Unlike some of the others,” he said, “we still think the reason people go to the movies is to see movies.”

© 2014 The New York Times Company