It's not just young indie bands and ladette singer-songwriters whose lives have been transformed by internet exposure. Take a quick browse around YouTube, and you'll find countless clips of a bunch of young black guys from Chicago bearing all manner of brass instruments, blowing up a storm in various sites around the world: a Berlin underground station, a Parisian shopping mall, a New York street corner, wherever. Like some internet virus become human, the Hypnotic Brass Band seem to be everywhere at once, spreading a little joy and jazz around. Just don't call it busking.
"There's feeling and strategy and potential in our music," says Gabriel Hubert, one of the nine-strong ensemble's four trumpet players. "We don't call it busking, we look at it as marketing and promotion. So we pick our sites carefully, to get people talking about us: because when people talk, rumours spread, and that means you're being exposed to more and more people. And that allows us to grow in the hearts of everyday people. So when you grow, they grow with you."
A sign of how much their audience has grown with them can be gleaned from those YouTube clips, which are entirely, Hubert stresses, the work of their fans. "Not one member of the Hypnotic Brass Ensemble has put up a clip on YouTube," he confirms. "It's all from our fans, whom we love dearly."
Brass bands are, of course, far more abundant in America than Europe, there being a well-established national tradition of High School marching bands, along with a separate, parallel strain in New Orleans which developed out of the tradition of funeral bands such as George Lewis's Eureka Brass Band, whose modern-day successors are such as the Hot 8 and Rebirth Brass Bands. But the Hypnotic Brass Ensemble comes from outside either tradition, being rooted more in the Chicago soul and jazz heritage. "We never really got into the New Orleans marching-band style, but we have a lot of respect for it, and Wynton Marsalis has given us a lot of encouragement," says Hubert. "We want to re-birth that Chicago brand, from Quincy Jones and Curtis Mayfield and Earth, Wind & Fire, but with a youthful spirit."
Apart from drummer Christopher Anderson, the eight horn-playing members of the Ensemble are all sons of jazz trumpeter Phil Cohran, who was part of Sun Ra's Arkestra during its tenure in Chicago, and went on to become one of the founders of the Association for the Advancement of Creative Musicians (AACM), the city's support group for proponents of avant-garde jazz.
"Sometimes, parents have a plan for their children that the child doesn't necessarily see till later in life," explains Hubert. "[Our father] didn't want his music to be closed out of music history – because his music informed not just Sun Ra, but Curtis Mayfield and Earth, Wind & Fire, too – so he wanted to teach his children to spread that knowledge of music, its origins, how to heal people with it, that kind of stuff. We're still trying to fill his shoes."
Cohran schooled his children from an early age, teaching them not just how to play the various horns, but the theoretical knowledge of how one note relates to the next, the principles of families of notes. By the time they started high school, they were experts compared to their peers.
"Our older brother and sister were already in the school band when we got to high school," recalls Hubert, "and they needed extra pieces in the band, so we joined them straight away. We had to learn to work together, but we have a common goal. Music will be a something we'll pass on to the next generation."
Their father's influence wasn't simply musical, either; alongside that, he instilled in his children a strong sense of self-determination which led to their penchant for street performance, and to their rejection of major-label offers.
"When rap started, the DJ was important, he was the one who put the music together," he says, "but somewhere along the line they got left behind, and the rapper became more and more famous. But we want respect for the musicians, we want to recapture the mood of respect from earlier times for Monk, Miles, Bird and Coltrane."
Accordingly, they chose to pursue their own path, on their own terms, even if that meant playing in the street.
"You can bring something to the world that you didn't know you had until you looked for it," Hubert explains. "And if you plan and strategise, you can put yourself in positions where you can be seen by the people you want to be seen by." In the Hypnotics' case, that careful exposure has led to work with the likes of Mos Def, Erykah Badu, Maxwell, and Afrobeat drummer Tony Allen, with forthcoming alliances with Damon Albarn and Red Hot Chili Peppers' bassist Flea planned.
"We look forward to all of it, it's all moving forward," says Hubert. "What we want to do is be crusaders for the musicians, because the musicians are important: you might be able to sample things through a keyboard, but a keyboard can't duplicate heart. People take music for granted, but you can't imagine a day when the bird didn't get up and sing for you."
The Hypnotic Brass Ensemble will perform at Cargo, London EC2, 29 January, with Tony Allen and the night will be recorded for Red Bull Music Academy Radio. Their album will be released through Honest Jons in May