Tulane University accounting major Ethyn Samuels finds his true passion in his off-hours, on Monday and Thursday nights, when he gets together with 14 other Tulane students to sing.

Samuels, 20, can remember when he was in middle school and only a small group of people were interested in close-harmony singing. Not anymore. “More and more people are seeing the super-awesomeness of a cappella (singing),” he said. “It’s red hot.”

On Saturday night, Samuels’ singing group, Green Envy, will be featured at the Ernest N. Morial Convention Center as part of the Barbershop Harmony Society’s winter convention.

Green Envy, which sings in a contemporary, non-barbershop style, will perform a few numbers but will also collaborate on a version of the Eagles’ song “Seven Bridges Road” with a barbershop quartet, Forefront, that won a silver medal in a recent worldwide contest.

The society, which has sought to promote and preserve barbershop singing since 1938, used its philanthropic arm to pay for the lodging of 500 young singers who came to New Orleans to perform at the convention. The young men have enlivened a musical genre that once seemed doomed to live on only through TV reruns of “The Music Man” and through Lions Club quartets performing at small-town retirement parties.

But on Friday, 17 youth choruses from across the country and Canada crooned their way through short sets in front of an audience of 1,600. Most songs ended with typical barbershop choreography, with the front row bending down on one knee, arms outstretched.

In the Convention Center lobby, teenagers seemed to move back into this century as they unbuttoned sequined vests, untucked satin shirts and pulled out iPads and earbuds. But still, there was overlap, as teens from out of town would stand in small circles and harmonize together, usually for the well-known “tag” — the passage that ends each song.

Then one would pick up an iPad and look on www.barbershoptags.com for a new tag to sing together.

Barbershop singing is at its best as a casual, social activity, said society spokesman Brian Lynch, who said it has long been practiced by hobbyists who work by day as doctors, janitors and mechanics .

While women formed a parallel singing society called the Sweet Adelines International, the Barbershop Harmony Society was formed by two businessmen from Tulsa, Oklahoma. For years, the genre seemed the province almost exclusively of white, middle-class men, Lynch said.

But about 20 years ago, a New Orleans researcher, Lynn Abbott, published a paper about the African-American roots of barbershop harmonies. Abbott, now the assistant curator at Tulane University’s Hogan Jazz Archive, was honored Friday with an honorary lifetime membership in the society.

“His research led the way on this,” said Lynch, who said that researchers expanding on Abbott’s work have found that black quartets originated four-part close-harmony singing but soon were overshadowed by white quartets, singing the same harmonies, who landed record contracts and found fame as a result, rendering the genre’s black roots nearly invisible.

Abbott discovered that the earliest documents describing the quartets talked about black groups . Around the turn of the 20th century, figures such as black writer and educator James Weldon Johnson talked about how common quartets were in the black community before the style was picked up by white singers.

Abbott realized how common the style was as he rooted through junk stores, looking for old blues recordings. “Anytime I would come across a stack of old blues records, there would also be a stack of these quartet records,” Abbott said. “It told me that the style was extremely popular in the black community, but we didn’t know anything about it.”

When Abbott listened to the records, what he heard was the close-harmony singing that is now commonly known as barbershop. He found that nearly every black church, school, social club and fraternity had its own quartets. “It fairly well saturated the city of New Orleans at the turn of the century, for people of every age,” he said.

The society’s conference this weekend still featured a lot of gray hair in its audience and a very prominent Seniors Quartet Contest for singers over 55. But the genre has expanded and diversified in ways that many could not have imagined, thanks to wildly popular a cappella groups like Pentatonix, which had last year’s top-selling Christmas album, and shows like NBC’s “The Sing-Off,” a televised competition for a cappella groups.

Green Envy, which was founded at Tulane in 1991, includes both women and men and has only a handful of music majors, who sing alongside students majoring in molecular biology, premed, psychology, anthropology and business.

Samuels is the vocal percussionist, or “beatbox,” a technique he learned in high school after trying out three times and not making it into his school’s a cappella group as a vocalist singing a more traditional part.

He was determined to be part of that group, Samuels said, remembering the day in middle school when an a cappella group first performed for him and his classmates.

“There was something so utterly appealing of having everybody play the same instrument. Their instrument — their voices — blended together in a way that a band never could.”