We're revisiting archival interviews with some of the musicians featured in the documentary 'Summer of Soul.' The film is about the 1969 Harlem Cultural Festival, a series of free concerts which reflected changes in Black culture and politics. Today we'll hear our 1996 interviews with B.B. King, perhaps the most famous blues singer and guitarist of his generation, and our 1988 interview with Hugh Masekela, the South African trumpeter who was described in the 'New York Times' as a symbol of South Africa's anti-apartheid movement, even as he spent three decades in exile.