Of all the things to slice through New Orleans summer heat, the sweet sound of Jonté Mayon in vocal flight spilling out onto Decatur Street from B.B. King’s Blues Club is perhaps the finest. It comes as no surprise that she’s been singing her entire life.

“I am the youngest child of four,” she said. “We were a musical household. We sang commercials. Even made harmonies of the words my mom would use to scold us. I was part of the family group the Landrum Singers when I was three.”

Jonté’...