Legaci, four Filipino-American rhythm and blues singers from the San Francisco Bay area, just might be the most visible yet invisible pop figures in the world.

Before becoming backup singers to the teen pop heartthrob Justin Bieber, they were rising stars on YouTube, now a crucial launching pad for Asian-American artists seeking the kind of exposure rarely afforded them by the mainstream recording industry.

“The stereotype is that we’re violinists or mathematicians,’’ the cultural critic Oliver Wang said. “So for a lot of industry executives there’s this disconnect when they see an Asian-American singing R&B. But YouTube is chipping away at that. It’s becoming a much more common sight.’’

Micah Tolentino, 30, started Legaci under the influence of R&B acts like Boyz II Men and Shai, in 1997, while in high school in Vallejo, California.

“Even if most people just know us as Justin Bieber’s Asian backup singers,’’ Mr. Tolentino said, “we’re proud to be out there, to show the world that Asian-Americans are talented.”

The pop charts have not been hospitable to Asian- Americans in the United States.

“Asian-Americans are locked out,’’ said Phil Yu, who runs the pop-culture blog angryasianman.com. “There are definitely elements of racism, but it’s also that audiences are not used to seeing Asian faces on the pop charts or on music videos, and record labels won’t take a chance on that.”

Legaci can list its fellow travelers on one hand. There’s the Pussycat Doll Nicole Scherzinger (her father is Filipino), the fledgling Filipino pop star Charice (who sings a duet with Iyaz on her first United States single, “Pyramid” ) and most famously, Allan Pineda, also known as Apl.de.ap, of the Black Eyed Peas.

“Mostly when you see Asian artists, it’s as D.J.’s or producers,” said Mr. Pineda, who was born in the Philippines and immigrated to Los Angeles when he was 11. “We’re always part of the background scene. We’re like the quiet storm.”

Mr. Pineda has sneaked two songs in Tagalog, a Filipino language, onto Black Eyed Peas albums. He has started his own Asian-focused record label, Jeepney Music, and recently recorded “Take Me to the Philippines” under the auspices of the Philippine Tourism Department.

The one place where Asian-American artists flourish in contemporary pop is on YouTube.

Last month, the ninth-most-subscribed YouTube musician channel belonged to the Korean-American pop singer David Choi . Of the 50 most subscribed music channels, four belonged to Asian-American artists: AJ Rafael (178,117 subscribers), Kina Grannis (177, 560), Gabe Bondoc (143, 881) and Cathy Nguyen (140, 904). Ms. Nguyen’s version of Jason Mraz’s “I’m Yours,’’ from a year ago, has topped five million.

“Asian-Americans want to see people who look like they do, who reflect their lifestyle, who speak English the same way they speak English,” Mr. Yu said.

“Now for a kid growing up the most famous personality for them is not necessarily Lady Gaga but David Choi.”

The amateur aesthetic at the heart of YouTube had long been part of Legaci’s own upbringing. Its members all grew up singing pop and R&B hits on the karaoke machines of their Philippines-born parents.

“Filipino culture is based on performing,” Legaci’s Chris Abad, 28, said. “In the Philippines you are raised to have music as part of your life. Our parents put that into our minds at a very young age.”

It was Legaci’s version of “Baby,” the hit by Mr. Bieber, that changed everything.

The video, on which they were joined by Ms. Nguyen and the rapper Traphik (another YouTube mainstay), was barely up for one day when the group received a call from Scooter Braun, Mr. Bieber’s manager, who just three years ago had discovered Mr. Bieber in much the same way, watching him perform his own cover versions on YouTube. Mr. Braun was so impressed with Legaci’s take on the song that he invited the group to join Mr. Bieber.

The group has been pleasantly surprised by just how much it has been embraced by Mr. Bieber’s fans.

“We know how long it’s taken African- American groups to be totally accepted by the mainstream,” said Delfin Lazaro, 28, of Legaci.

“That will happen for Asian- Americans too. We want to open that door, and then we’ll bring everyone with us.”


By JOSH KUN