"Mood Indigo" was composed in October 1930, credited to Duke Ellington, Barney Bigard, and Irving Mills, though its origins are more complex. The main theme originated as a melody called "Mexican Blues" by New Orleans clarinet teacher Lorenzo Tio Jr., which Bigard learned from Tio and brought to Ellington, who then created the revolutionary arrangement. Mitchell Parish wrote the lyrics, though Mills received the credit. Originally titled "Dreamy Blues," the piece was written specifically for a radio broadcast and generated such an enthusiastic response that lyrics were quickly added. The composition's most groundbreaking feature is Ellington's inversion of conventional front-line voicing: rather than placing the clarinet highest and trombone lowest, he reversed the order, with the trombone sitting at the very top of its register and the clarinet playing at its lowest range. Combined with tight muting on the trombone, this voicing creates what engineers call a "mike-tone," an acoustic illusion where overtones from the clarinet and muted trombone interact to produce the perception of a ghostly fourth instrumental voice. Duke Ellington and His Orchestra first recorded the tune for Brunswick Records on October 17, 1930, and the piece became one of the tunes most closely associated with the band throughout its fifty-year history. Frank Sinatra recorded a notable vocal interpretation in 1955, arranged by Nelson Riddle. The 1930 Brunswick recording was inducted into the Grammy Hall of Fame in 1975, and the composition remains one of the most celebrated standards in the jazz repertoire.
