Seville, Spain (CNN) — The air in the small basement room is thick with perspiration as seven young women stamp their feet in the same complicated rhythm again and again, still not getting it quite right.
Their hard heels relentlessly strike the wooden floor, throwing up a deafening clatter as they're pushed to perfection, or almost to the breaking point.
The next room, just as sweaty, is filled with another wall of sound, this one created by a platoon of guitarists.
Their synchronized strumming intensifies as numbed fingers fly over frets and strings, struggling to match a tempo that keeps getting faster and faster.
And at the end of the corridor, in another smaller room, seated around a twirling dancer, a group claps its hands in time to a mysterious beat.
Their formidable instructor regularly halts the class to chide her pupils over seemingly minor imperfections.
These are everyday scenes at the Heeren Flamenco Foundation (Avenida de Jerez, 2, Seville, Spain; +34 954 21 70 58), a cheerful blue-walled institution currently housed in the shadow of a soccer stadium on the southern fringes of the Spanish city of Seville.
Heeren specializes in schooling singers, guitarists and dancers in the technical skills needed to perform the art that has come to symbolize Seville and the surrounding region of Andalusia.
It's no shock to find that it takes hard work to reach the high standards expected by flamenco audiences in Spain and around the world.
What is a surprise though is the number of non-Spanish students hoping to reach this level.
"About half of the people studying here are from other countries," says Cristina Heeren, a Columbia University alumnus who created her namesake foundation two decades ago, building it into one of Seville's most respected.
"Last year we had 28 different nationalities, from all over the world. Many from Asia, including South Korea and sometimes China."
The surge in foreign applicants comes at a time when Spain is in the grips of an economic crisis, reportedly limiting the number of homegrown flamenco students.
It's a situation that's led to headlines asking whether these non-Spaniards are the "saviors of flamenco."
On the streets of Seville, it's hard to see flamenco as anything but 100% Spanish.
It's as much a part of the city's identity as the large, bitter oranges dangling from its trees.
Department stores and boutiques offer racks of colorful and expensive flamenco outfits. There are flamenco fashion shows and fiestas.
Distinctive flamenco rhythms can be heard everywhere, with locals (and even down-and-outs) regularly bursting into song, precision hand clapping and dancing.
But with seemingly impenetrable rules, beats and cadences drawn from a rich cultural history, can those born outside the region ever really match the skills of locals?
"You have to be talented and you have to work very hard, but it is possible," says Tino van der Sman, a tall, blond flamenco guitarist from the Netherlands who now performs with some Seville's top dancers and singers.
Just minutes earlier, Van der Sman was on stage at the Casa de la Memoria (Calle Cuna, 6, Sevilla; +34 954 56 06 70), one of the city's prestige flamenco showcases, accompanying a trio of singers and dancers through some intense displays of traditional Spanish artistry.
If the audience was disappointed to see a Dutch musician, they didn't show it in their applause.
"Spanish people don't have a problem with me playing, if there's anyone who doesn't respect me it's foreigners who think I don't fit in with their image of a flamenco guitarist," he says.
Van der Sman says he's been playing the guitar for nearly 30 years but only reached a professional flamenco standard after moving to Seville to study.
Since then, he's performed all over the world.
He says he's not the only non-Spanish artist pursuing a career in flamenco, with some of the dancers he works alongside originating from overseas.
"It's a natural thing," he says. "Throughout its history, Spain has been influenced by foreigners. Seville itself has hosted Arabs and Jews."
Even flamenco's Spanish stars welcome the idea of outsiders entering the profession.
Rocio Molina, a celebrated dancer whose "fusion flamenco" collaborations with hip-hop performers and other artists has attracted the ire of traditionalists, says the profession's future lies in "breaking down barriers."
She insists, however, there's no substitute for learning in the craft in Andalusia.
"Seville is a perfect place to study flamenco, because you don't just learn in a studio or an academy, but in the street itself," she tells CNN.
"It's a way of life you can connect with other people. Because there are a lot of people with a lot of art here.
"You just have to express yourself and you will learn a way of life."
Cristina Heeren also claims anyone can learn flamenco's "mathematical" structures, even if some of her less talented students do need to have their expectations managed about their potential.
However, she's worried about outside influences on the art form.
"I don't like this fusion," she says. "Flamenco is very fragile and if it's introduced to something foreign it degrades, it loses its possibilities.
"Flamenco is much more structured than people think, it has got very strict boundaries.
"It is so rigid it forces the artists to work within that framework and come up with new versions that do not sound like anything except flamenco but that fit perfectly."
Back in the Heeren academy's basement, the young women learning flamenco footwork grab a much needed breather.
Among them is Zenora Bharos, a 32-year-old from Suriname who's taking a year-long career break from her work as a medical doctor to study flamenco dance.
She says it's challenging and tough on her body, but not impossible.
"It is really difficult to condition yourself, you think, 'how do I coordinate my footwork with my arms?
"Then you feel more confident with the footwork then you work on the arms and finally it all becomes one.
"Anyone can do this if they really want to. It can be hard, you need passion and you have to love it.
"But if you put in the effort, the practice and discipline it's doable."