Janis Joplin was called “the greatest white urban blues and soul singer of her generation” by the Rock and Roll Hall of Fame, which inducted her in 1995. Joplin’s powerful, gritty vocals made songs like “Piece of My Heart,” “Ball and Chain,” “Summertime” and “Me and Bobby McGee” uniquely her own. Joplin, who died in 1970 at age 27 of an accidental drug overdose, burst on the music scene in 1966 as vocalist of San Francisco’s Big Brother and the Holding Company. The band’s manager, Chet Helms, encouraged its members to make Joplin their lead singer. Joplin’s triumphant performances at…