It happens mostly at the airport. Or when they’re getting on an elevator.

Wil Baptiste says when he and longtime friend Kevin Sylvester are spotted carrying their musical instruments cases, people usually assume that saxophones or trumpets are inside.

Nope.

Instead, those strangers are surprised to learn that the two black men from south Florida actually play viola and violin.

They’re the members of Black Violin, a renowned duo that does something striking: playing classical music on top of hip-hop beats.

“You don’t typically see brothers like us playing the violin the way that we do, or ever, in any way, to be honest,” Baptiste explains. “The reaction is always: ‘Wow. Where did you guys study?’ Honestly, people don’t really think we even studied anywhere. They kinda think we just picked it up.”

Both are classically trained — Baptiste on viola and Sylvester on violin. And they’re just as comfortable playing Brahms as they are Biggie Smalls.

In fact, they’re quite successful at it. Their most recently album, 2015’s aptly titled “Stereotypes,” hit No. 1 on Billboard ‘s classical crossover chart and No. 1 on the magazine’s R&B albums chart. The video for their song ‘A Flat’ has racked up more than 8 million views on YouTube.

Black Violin will play back-to-back shows in New Jersey next week: Wednesday, April 11, at the Bergen Performing Arts Center in Englewood and Thursday, April 12, at State Theatre New Jersey in New Brunswick.

Baptiste says when he was younger, he was bothered when people were stunned to learn what instruments they play. But no longer.

“Our society has painted the picture of someone that looks like me in a certain way,” he says. “So when that perception is shattered, it makes people think. And I’m okay with that. I’m okay with doing something that will make people view other people differently. I think what I’m doing on stage is breaking stereotypes and bridging the gap between these two different genres — classical and hip-hop — but also bringing people together. Now I look at it more of like: It’s good work being done.”

That Baptiste and Sylvester — who go by the stage names Wil B. and Kev Marcus — play string instruments at all is a stroke of fate.

Baptiste originally wanted to play saxophone.

“I used to beat on the table (in school), and the security guard would get upset at me,” he recalls. “He told me he used to play the sax and make money on the weekend playing gigs. I thought to myself: ‘I need money.’”

But when Baptiste tried to enroll in a summer program to learn the sax, he was put in the wrong class — and stuck with viola.

“I had to live with it,” he says. “But after a couple of days, I kind of grew interested in it.”

Sylvester, meanwhile, was forced into violin lessons when he was caught stealing candy from a store, and his mother put him in a music class.

The two met in high school at Dillard High School of Performing Arts in Fort Lauderdale, Florida. They went to different colleges to study music — Baptiste at Florida State University, Sylvester at Florida International University.

But they reconnected after that — and stumbled into their sound.

“It’s definitely not something we methodically thought up,” Baptiste says. “We didn’t wake up and say, ‘These two genres would be cool together.’ I think it’s really the product of our environment. We grew up in the hood, and we happened to play a stringed instrument. And to us, hip-hop is about expression. And we knew the instruments. We knew the violin. We knew the viola. What better way to express ourselves than something we knew? And it was just really having fun.”

They took their name from a 1965 album called “Black Violin” by jazz violinist Stuff Smith.

“Kev’s professor gave it to him on his first day of college,” Baptiste remembers. “He listened to it, and he really loved it, and it really inspired him to think outside the box. And he sent it to me, and it did the same. And it’s something we still listen to today.”

Originally, their goal was to be producers like The Neptunes – the famed production group featuring Pharrell Williams – but their performances caught on with audiences. They surprised venue owners in south Florida who were leery of booking classical musicians at dance clubs.

Their big break came in 2005, when they won “Showtime at the Apollo” — the legendary talent competition at the Apollo Theater in Harlem.

Since then, they’ve opened for or collaborated with everyone from Kanye West, Alicia Keys, Wu-Tang Clan and Wyclef Jean to Tom Petty, Aerosmith and Mike Shinoda of Linkin Park.

They’ve played at the South By Southwest and Bonnaroo festivals. They composed the score for the Fox TV show “Pitch.”

And they performed at President Barack Obama’s second inauguration, in 2013.

Baptiste’s favorite collaborator?

“I think Mike Shinoda of Linkin Park. And Alicia Keys,” he says. “They’re both incredible. And everyone else really showed a lot of love. Alicia Keys, we sat and talked to her and she’s really humble. And Linkin Park showed us how millionaires who have sold a lot of records should treat people.”

But who was he the most starstruck over?

“None of them,” Baptiste says. “I was actually the most starstruck when I met Earth, Wind & Fire. I’ve been a fan of them for a long time. When I met them at the Billboard Awards, I was like, ‘Yo, that’s crazy. Earth Wind & Fire.’”

Fair enough. But who would he pick if he could have only one artist’s music on his phone for the rest of time?

“Wow,” Baptiste says when asked. “I would have to choose — oh, this is difficult. I’d say Curtis Mayfield.”

Black Violin average about 150 shows a year, touring with DJ SPS and drummer Nat Stokes. This week, they’re playing back-to-back shows at the venerable Kennedy Center in Washington, D.C.

Baptiste said New Jersey audiences next week can expect a “high-energy show.”

“It’s a lot of fun,” he says. “We encourage the crowd to get up and dance. There’s highs and lows in the show. Just expect the unexpected. Whatever you think you’ve seen from videos online, trust me: It doesn’t do it justice. If you want to experience something completely different, this is the show for you.”

The duo is also in the studio now working on a new album. A release date is yet to be determined.

Baptiste says there’s another thing he’s proud of: Drawing in people who might not otherwise listen to classical music.

“Particularly kids,” he explains. “They’re into classical now. Actually, they’ll pick up the violin because of us and how we approach it. It’s really incredible to see how something you think is this way, but when you see us introduce it another way, you look at it completely different, and it opens up this world.”

So does he ever wish he actually got to play saxophone all those years ago?

“No,” Baptiste says bluntly. “Absolutely not. I play a lot of different instruments, but I still haven’t picked up the sax.”

Black Violin will perform at bergenPAC on Wednesday, April 11, and at State Theatre New Jersey on Thursday, April 12. Visit their sites for tickets and more information.