The One Voice Children’s Choir has grown since the days when founder-director Masa Fukuda squeezed 45 folding chairs into the living room of his apartment for rehearsals. “My downstairs neighbor hated me,” said Fukuda, who now makes his home in Sandy with his wife, Alyssa.

Rehearsals now are split into two weekly sessions, one at a middle school in Salt Lake County and the other in Utah County. (It’s all the same choir, so singers simply choose the rehearsal that’s more convenient.) Children travel from as far away as Wyoming and Idaho to participate. One Voice is a nonprofit corporation with a board of directors and many parent volunteers.

There are 140 singers in the choir, but it’s rare for them all to appear together, partly because of space considerations and partly because these are kids 4 to 18 years old, not full-time entertainers. About 100 of them will perform with Kurt Bestor and his band this weekend as part of the popular entertainer’s 30th-anniversary Christmas shows; One Voice was one of four guest acts chosen by fan vote.

Don’t worry if you can’t catch Saturday afternoon’s show. The choir makes around 50 appearances a year, including Monday’s Christmas Carole Sing-Along at the Vivint Smart Home Arena.

(Steve Griffin | The Salt Lake Tribune) Masa Fukuda directs the One Voice Children's Choir during a concert at the Joseph Smith Memorial Building in Salt Lake City on Friday Dec. 8, 2017.

Many of those performances are in support of charitable causes such as Operation Smile or the Ouelessebougou Alliance. “So much of our family’s world has expanded beyond Bountiful, Utah, and Salt Lake City because of this group,” said Stephanie Hess of Bountiful, whose daughter Kenzie, now 18, has been singing with One Voice since she was 7.

“I’ve gained a lot of friendships that I’ll probably have for a very, very long time,” Kenzie Hess said. “I’ve learned to really appreciate what I have.” Performing for charity “helps me to be grateful,” she said. “People have problems that are way, way bigger than what I go through.”

The choir started out as the official children’s choir of the 2002 Winter Olympic Games in Salt Lake City. Fukuda — a native of Japan who came to Utah as a high-school exchange student and decided to stay — recruited members from nearly 70 local schools to sing a song he co-wrote, “It Just Takes Love,” on the Games’ commemorative CD. The children enjoyed performing together so much that they kept going. In 2003, while still known as the Studio A Choir, they won the John Lennon Dream Power Music Award after singing for Lennon’s widow, Yoko Ono, in a competition in Japan. In 2014, they were contestants on “America’s Got Talent.”

“You don’t see us in competitions … usually,” Fukuda said with a grin. But the “AGT” offer, which entailed NBC not only covering the group’s expenses but giving the kids a per diem so they could see a Broadway show, was too much to turn down.

Although some choir members have branched out and found success on YouTube and beyond — Lexi Walker being the most notable example — “we are not an ‘American Idol’ factory,” Fukuda said, adding he has referred some prospective singers with grand ambitions to talent agencies instead. “We interview each child and their parents — why do they want to join?”

“The parents sometimes want things their kids don’t necessarily want,” Alyssa Fukuda said.

There are opportunities for solos, but Masa Fukuda strives to keep the competition friendly. “It’s very powerful to clap for them and cheer them on,” said Abbie Scott, 14, of Midway. “It’s really powerful not only when you’re the soloist, but to be encouraging of others.”

The young singers and their moms said Fukuda is another element of the show. “Masa’s energy inspires the kids to feed off each other,” Stephanie Hess said.

(Francisco Kjolseth | The Salt Lake Tribune) Masa Fukuda, a songwriter, music arranger and director of the One Voice Children's Choir joins his wife Alyssa Fukuda in her classroom at Granger High School where she teaches Japanese. Set up by a friend in July of 2015, the two married a few months later in October.

“I guess I turn into a showman,” he said. But he declines to sing in public — the exception being his October 2015 wedding reception, when he fronted the choir in a rendition of Alyssa Fukuda’s favorite song, Coldplay’s “Yellow.” The Fukudas, each of whom served a Mormon mission in Japan and graduated from Brigham Young University, were set up on a date by a mutual friend whose daughter was in the choir. Alyssa spends as much time on choir business as her job teaching Japanese at Granger High permits.

There are no age divisions in the choir; when boys’ voices change, they switch to tenor. The average age of singers a few years ago was 10, but it’s crept up to 12 or 13 “because no one wants to quit,” Masa Fukuda said. There are 16 open slots this year, and 260 children have applied.

(Steve Griffin | The Salt Lake Tribune) Members of the One Voice Children's Choir prepare for a concert at the Joseph Smith Memorial Building in Salt Lake City on Friday, Dec. 8, 2017.

“I really like interacting with kids of all ages, not just my own friend group,” said Abbie, who joined nearly six years ago. “Of course there are lessons about singing and blending, but also about being happy for others and encouraging them.”

“At the end of the day, I always love it when people come talk to us and say, ‘Thank you; you touched my heart and lifted me up,’ so much more than, ‘You guys sounded so great,’ ” Fukuda said. “The biggest thing is not so much to sing the right notes with perfect diction — that’s important, but there’s far more to it.”

Bestor fest

The One Voice Children’s Choir will perform on Kurt Bestor’s Christmas concert as one of four musical guests chosen by popular vote.

When • Saturday, Dec. 16, 2 p.m.

Where • Eccles Theater, 131 S. Main, Salt Lake City

Tickets • $32.50-$57.50; artsaltlake.org

Also • Actor-singer Dallyn Vail Bayles will headline Bestor’s 8 p.m. show on Saturday