BUENOS AIRES — The crowd at a recent concert exploded into rapturous cries as the group’s frontman walked onto the stage and began setting a drum beat, launching his band on an improvised journey across musical genres that culminated an hour later in a standing ovation.
Over a 30-year career, Miguel Tomasín has released more than 100 albums, helped turn his Argentine band into one of South America’s most influential underground acts, and helped hundreds of people with disabilities express their voices through music.
Mr. Tomasín has achieved this in part because of a distinctive artistic vision that comes, his family, fellow musicians and friends said, from having been born with Down syndrome. His story, they say, shows how art can help someone overcome social barriers, and what can happen with an effort to elevate a person’s talents, rather than focusing on their limitations.
“We make music so that people enjoy it,” Mr. Tomasín said in an interview at his home in the windswept Argentine city of Rio Gallegos, near the country’s southern tip. Music is “the best, magical,” he added.
Though his prolific output has not achieved commercial success, it has had a significant impact on how people with disabilities are perceived in Argentina and beyond.
It has also inspired members of his band, Reynols, to establish long-running music workshops for people with disabilities. And other musicians they have worked with have started more bands whose members include those with developmental disabilities.
“Thanks to Miguel, many people who had never interacted with a person with Down syndrome were able to become aware of their world through music,” said Patricio Conlazo, an occasional Reynols member who, after playing with Mr. Tomasín, started music projects for people with disabilities in southern Argentina.
Reynols’s unconventional approach to music has also inspired established musicians.
“I was reminded by him that you can play music as you like,” said Mitsuru Tabata, a veteran Japanese experimental musician who has recorded with Reynols.
But the band’s freewheeling sound has its detractors, too.
A prominent British music journalist, Ben Watson, called their music “annoying racket,” in his 2010 book “Honesty Is Explosive!” where he suggested that Mr. Tomasín’s presence in the band was a publicity stunt.
In its first years, the band struggled to find venues and labels interested in their improvisational sound. A turning point came nearly a quarter century ago, in 1998, when they unexpectedly became a house band on an Argentine public television program, which exposed them to a new audience.
The job made Mr. Tomasín the first Argentine with Down syndrome to be employed by a national broadcaster.
“It was revolutionary, because people with these conditions were largely hidden from public view,” said Claudio Canali, who helped produce the program.
A New York Times reporter and a photographer spent a week in Argentina to interview Mr. Tomasín and document his life, both in Buenos Aires and Rio Gallegos. Mr. Tomasín speaks in short phrases that are largely understandable to a Spanish speaker, but sometimes require an accompanying relative to put them in context.
Mr. Tomasín is 58, though, like many other artists he lowers his age, insisting he is 54.
He was born in Buenos Aires, the second of three children of middle-class parents. His father was a Navy captain, his mother a fine arts graduate who stayed home to raise the children.
In the 1960s, most Argentine families sent children with Down syndrome to special boarding schools, which in practice were little more than asylums, according to his younger sister, Jorgelina Tomasín.
After visiting several of them, his parents decided to raise Mr. Tomasín at home, where he was treated no differently than his siblings.
He started showing interest in sounds as a toddler, banging on kitchen pots and playing with a family piano, prompting his grandparents to buy him a toy drum kit.
Later, after coming home from school, Mr. Tomasín would go straight to his room and play all three cassettes that he owned from beginning to end, making the crooners Julio Iglesias and Palito Ortega an inescapable house presence for years, Ms. Tomasín said.
By the early 1990s, the close-knit household began to separate, as his siblings grew up and left home, leaving Mr. Tomasín, by then a young adult, feeling isolated.
To fill the void, his parents decided to send him to a music school, but struggled to find one that would accept him.
One day, in 1993, they tried an unassuming place they came across while shopping in their Buenos Aires neighborhood, the School for the Comprehensive Formation of Musicians, which was run by young avant-garde rockers who taught classes to subsidize their rehearsal space.
“‘Hi, I’m Miguel, a great famous drummer,’” Roberto Conlazo, who ran the school with his brother Patricio, recalled Mr. Tomasín saying at their introduction, despite his having never, up to that point, touched a professional drum kit.
The school became an unexpected artistic home for Mr. Tomasín. In a country that remains deeply divided by the legacy of a military dictatorship and a Marxist insurgency, it was rare for a military family to even associate with bohemian artists, let alone entrust a child with them.
But Mr. Tomasín’s family and the artists ended up becoming lifelong friends, an early example of how his lack of social prejudices has influenced others to reconsider long-held assumptions.
His spontaneity and lack of insecurities made Mr. Tomasín a natural improviser, and an ideal fit for the school’s goal to create music without preconceived ideas.
“We were looking for the freest musical universe possible,” said Alan Courtis, who taught at the school. “Miguel became the alarm that woke up the dormant side of our brains.”
Roberto Conlazo and Mr. Courtis had already been playing in a group that eventually would become Reynols, a name loosely inspired by Burt Reynolds.
After giving Mr. Tomasín some drumming lessons, they decided to bring him into the band. Their collaboration, however, got off to an uncertain start.
During one of their first shows, in 1994, a crowd of high school students broke into a mosh pit, which Mr. Courtis and Roberto Conlazo stoked by spraying deodorant into the audience’s faces, pulling out guitar strings with pincers and emitting bloodcurdling noise from primitive loudspeakers.
When Mr. Tomasín’s father, Jorge Tomasín, approached the band after the show, they were resigned to never seeing Miguel again, sure his father would disapprove.
“‘Lads, I didn’t understand a lot of what you played,” Roberto Conlazo recalled the father saying, “‘but I saw Miguel very happy. So go right ahead.’”
Those words were a green light for the ensuing three decades of creativity that has produced around 120 albums, American and European tours, and collaborations with some of the world’s most respected experimental musicians. Reynols splits proceeds from shows and music sales equally, making Mr. Tomasín one of the few professional musicians with Down syndrome in the world.
The band first came to broad national attention with the afternoon TV gig. A popular host, Dr. Mario Socolinsky, had interviewed Reynols on his daytime program, “Good Afternoon Health,” in which he gave health tips. Impressed with Mr. Tomasín’s integration into the band, he invited them to be the show’s house musicians, giving Reynols an unlikely job of playing to a mainstream audience five times a week for a year.
Reynols’s next break came in 2001, when Mr. Courtis and Roberto Conlazo went on the band’s first U.S. tour. Although Mr. Tomasín decided not to join them, the tour introduced his work to the global underground music network that has supported the band’s subsequent career.
In the following years, the band’s focus on improvisation drove its extraordinary output of albums. Because each jam session with Mr. Tomasín could result in a different sound, the band has released dozens of them as albums on small record labels in runs of a few hundred copies.
After seeing Mr. Tomasín’s performance on TV, families across Argentina started contacting the band, asking them to teach music to their children with disabilities. That led Mr. Courtis and Roberto and Patricio Conlazo to create a collective, called Sol Mayor, which brought together people with various physical and developmental disabilities to play music.
Their approach, they believe, puts a spotlight on the beauty of music that does not follow Western norms, like playing in an octave scale.
Inspired by work with Reynols, other musicians have started bands for people with disabilities in Norway and France.
Mr. Tomasín’s family say they were able to give him the support to develop his creativity thanks in part to their relatively well-off economic position, acknowledging the social inequalities that prevent many people with disabilities from reaching their potential.
At a recent sold-out Reynols concert in Buenos Aires, Mr. Tomasín sang and played all the instruments on the stage in front of 600 fans, posing for selfies with admirers after the show.
Earlier this year, Mr. Tomasín moved from Buenos Aires to Rio Gallegos to live with his brother Juan Mario, a former Army officer who now teaches English. In the afternoons, Mr. Tomasín dances to Argentine folk music, cooks and gardens at a local center for people with disabilities, often wearing his favorite Reynols T-shirt.
Mr. Tomasín’s bandmates say one of his greatest gifts is helping people become better versions of themselves without even being aware of his influence.
“He teaches without teaching, by simply enjoying his life,” Roberto Conlazo said.
Mr. Tomasín’s big plan for the near future is to stage a concert in his new town, bringing his bandmates from Buenos Aires, 1,600 miles away, and inviting his new friends.
“Let them come to my school,” he said, “so we can all play together.”
Hisako Ueno contributed reporting from Tokyo and Natalie Alcoba contributed research from Buenos Aires.