CHENGDU, China >> As the Happy Runxin and Glad Tidings performing troupes squared off in the Chengdu People’s Park on a recent morning, the newly installed noise monitors flashed to life, their digits registering each potential transgression by the park’s famously boisterous amateur dancers and musicians.

As Happy Runxin’s band struck up saxophones, trumpets, oboes and drums, a monitor next to the troupe flickered to life: 75 decibels. Then, while older dancers sashayed in red dresses before the hundreds of onlookers, a choir of dozens warbled, “Oh, motherland. Oh, motherland.” The volume jumped to 85 decibels.

Moments later, Glad Tidings opened an elaborate two-hour show a dozen yards away. Singers belted out, “We are the inheritors of Communism,” accompanied by three saxophones, a trombone, drums and an erhu, a Chinese two-stringed instrument, all played by retirees. Their designated monitor flashed: 82 decibels.

“They’re bigger than us, but more amateurish,” said Ye Jilong, a retired music teacher who helped conduct the Glad Tidings performance, a succession of patriotic odes. “Our troupe is more professional. It’s not whoever makes the biggest noise is the best.”

People’s Park has become famous for its colorful din. For years, choirs, bands and dance groups, mostly run by older residents, have jostled for space, audiences and glory. What they lacked in polish, they made up for with vigor. Residents gave the park the unofficial title of the “noisiest park in the world” — a boast for some, a lament for others.

“We keep our lives busy with collective activities like singing, dancing and mahjong,” said Ye, a burly 72-year-old. “You can find it all in the People’s Park.”

For their show, he and his singers had dressed in children’s school uniforms with the red scarves of Young Pioneers, a Communist youth organization. “Sometimes it got too loud,” he said. “You couldn’t hear me talking if you were in the park then.”

But lately the cacophony in the park has been turned down, helped by the reproachful noise monitors at each performance site.

In Chengdu, the capital of Sichuan province, and in many other Chinese cities, the raucous outdoor activities of older residents have ignited serious conflicts. Residents near parks often complain about the noise from amateur bands and dance groups, and brawls have broken out. City officials have been imposing noise limits and other regulations in People’s Park and others like it.

“For years, virtually every day, I’ve been disturbed by the racket from musical instruments, singing and disco dancing,” said one complaint about the park published on a city government website in 2014. “The People’s Park is just one big outdoor karaoke parlor,” said another online complaint.

Since last year, People’s Park has ordered bands and dance troupes to keep their noise level below 80 decibels. As Happy Runxin and Glad Tidings belted out song after song, nearby monitors showed the sound sometimes passing that level — reaching about as loud as standing near city traffic — but performers said momentary lapses were tolerated.

Still, the park is now much quieter than it was before, they said.

“Before it was chaotic,” said Deng Zixiao, 62, a retired doctor who has been going to the park to sing in choirs for eight years. “There was lots of fun, but there were also fights and complaints. We had to become more civilized.”

People’s Park was not always so noisy. It opened in 1911 on the former grounds of a Qing imperial encampment. High-rise buildings, malls and expressways have erased nearly all of old Chengdu, but the 28-acre park downtown has survived and holds one of the city’s few surviving old-style tea gardens, where people spend the day over cheap mugs of green tea.

Western people often treat city parks as a refuge for quiet relaxation. But in China, parks reflect an enthusiasm for organized collective leisure that is rooted in tradition and socialist values that many people absorbed under Mao Zedong, said J.P. Sniadecki, a filmmaker and anthropologist at Northwestern University, who made a documentary with Libbie D. Cohn about People’s Park.

“People’s Park does offer places for solitude and quiet,” Sniadecki wrote in an email. “But on the weekends, or at certain parts of the day, yes, it becomes a sea of people. The sense of collective space has roots in Chinese culture, well before the ‘collectivist’ era, though I am sure the socialist past contributes.”

The best-known symbols of this love of outdoor performance have been the “dancing grannies,” the groups of middle-aged and older women, as well as men, who sway and shimmy in unison to throbbing disco soundtracks and electro-folk songs that often irritate neighbors.

But the bebopping grannies are just part of the scene. On a recent morning, there were a dozen activities, including ballroom dancing and a kind of tai chi using rackets to sweep and throw balls. While some dancers moved with exacting discipline, others shuffled to their own rhythms. No one seemed to mind.

“You need to block your ears if you’re not used to it,” said Shuai Siqing, 63, a retired shop assistant doing gentle tai chi exercises right next to a group doing calisthenics to a frenetic folk-disco soundtrack.

“The noise doesn’t affect me,” Shuai said. “When you’re doing tai chi, you enter your own realm and ignore all that.”

The rising decibel levels stemmed in part from growing numbers of mobile karaoke operators who set up booming speakers the size of small refrigerators and charged people a dollar or so to sing along. The proliferating amplifiers engaged in an aural arms race, each trying to drown out the others.

“I don’t mind a bit of noise pollution — old people can also have their fun,” said Li Yu, who lived near the park and often walked through it with her daughter. “It got so loud I was worried about damaging my daughter’s hearing.”

Last year, park officials cracked down.

In Chengdu, officials banned the karaoke machines and shut down most performance spaces for months. Now 40 or so officially approved music and dance troupes must stick to a schedule that assigns them a space with sound monitors and sound barriers, participants said. If they become too noisy, a park guard comes over and warns them to hush.

“It’s a pity, but the park management was worried by all the fights and all the complaints from the neighborhood,” said Guan Weiming, 68, who sang with the Mass Passion Square troupe.

“China has too many people, so we have to learn to live together.”

© 2016 The New York Times Company