The word unique is vastly overused.  But Kelefa Sanneh has a style of writing and speaking about music that is most definitely his own.  It’s on the pages of his articles in The New Yorker and in his critically acclaimed 2021 book “Major Labels: A History Of Popular Music In Seven Genres.”  He heard a lot of music growing up, especially the African music of his parents.  But it was a mixtape at the age of 14 that opened the door to the rest of his life.