trombone shorty. [ applause ] reporter: to his fans, he is trombone shorty. first handed a horn at age 4. my younger brother, trombone shorty. reporter: troy andrews was nurtured for greatness. there he is with the legendary bo diddley. it was this city s music that saved troy from its violence. his talent a ticket to another world. sharing the stage with lenny kravitz just this year headlining jazz fest. now troy is sharing his gift. this is the trombone shorty academy at tulane university where high school students by the dozens get a free music education, renewing a loss tradition of musical mentorship. a lot of older musicians are not around anymore. the neighborhood was a different place after the storm. reporter: the storm, the scars of hurricane katrina