Although Joni Mitchell has shown jazz influences in her music since the album "Court and Spark," she has taken a quantum leap in that direction with her recent release, "Mingus."

The album is dedicated to the great bassist and composer Charles Mingus, who died earlier this year at the age of 57. Before his untimely death, Mingus had become interested in Mitchell's work, and hoped to collaborate on a musical project with her. Finally he composed six melodies to which Mitchell wrote the lyrics. The result of the collaboration is a sometimes confusing, often moving, and at times amusing album that presents a picture of both the complex man and consummate artist that Charles Mingus was, and the bold courageous talent that Joni Mitchell is.

The musical score is sparse, almost skeletal. Mitchell's rich voice, which some have compared to Billie Holiday's, serves to flesh out the score. High caliber musicians such as Jaco Pastorius, Wayne Shorter, Herbie Hancock, Phil Woods, Tony Williams offer background and embellishments but Mitchell's singing always takes the spotlight. Her mastery of complex jazz phrasings will simply amaze; and as always, Mitchell's voice is able to convey a tremendous range of emotion.

Tapes of Mingus in conversation serve to introduce or conclude songs, the best of which are "God Must Be a Boogie Man," about Mingus, "The Dry Cleaner From Des Moines," about an unlikely gambler on a hot streak, and the very bluesy, "Goodbye Pork Pie Hat," dedicated to the innovative sax genius, Lester "the Prez" Young.

"Mingus" is not easy to listen to, because it demands attention. The album is radically different from anything Mitchell has done before. She has pushed herself beyond preconceived limitations, producing an album that is a fitting tribute to Charles Mingus, the musician and the man. In that sense the album is a success and a true work of art.