Around 1975 , Mitchell 's vocal range began to shift from mezzo-soprano to more of a wide-ranging contralto . Her distinctive piano and open-tuned guitar compositions also grew more harmonically and rhythmically complex as she explored jazz , melding it with influences of rock and roll , R&B , classical music and non-western beats . In the late 1970s , she began working closely with noted jazz musicians , among them Jaco Pastorius , Wayne Shorter , Herbie Hancock , Pat Metheny , as well as Charles Mingus , who asked her to collaborate on his final recordings . She later turned again toward pop , embraced electronic music , and engaged in political protest . In 2002 , she was awarded a Lifetime Achievement Award at the 44th Annual Grammy Awards
44th Annual Grammy Awards
44th Annual Grammy Awards
Joni Mitchell