Once it was flirting with extinction. Now the brass band is alive and well and reshaping everything musical in its path. Even “The Flintstones” theme.

When the Onward Brass Band’s Paul Barbarin collapsed and died while marching in a 1969 Mardi Gras parade, it was darkly emblematic of the challenge facing New Orleans’ most beloved music. Many of the players who had defined the genre and kept it alive were fading out, with no obvious successors to re-invigorate the tr...