“More people in the United States listen to and enjoy jazz or near-jazz than any other music. Jazz is of tremendous importance for its quantity alone.” That was Marshall Stearns, one of the founders of academic jazz studies, writing in 1956 to argue why his subject was worthy of serious scholarship. As Nate Chinen says in his fascinating and vital new book, Playing Changes: Jazz for the New Century, that passage now sounds bizarre, like a report from “a vanished culture.” In fact, the music’s status today is the complete opposite: Most people vaguely recognize jazz’s cultural importance, but no one’s expected to get too excited about it