“People ask, ‘What do you do?’” Sean Ardoin says in a chat from his Lake Charles home. His answer? “I get to provide the atmosphere for people to choose to be happy.” He pauses a fraction of a second for emphasis. “I bring the happy.”

He brings it with his accordion and a zydeco beat and with Kreole Rock & Soul, which is both the name of his band and his term for his ever-expanding musical g...