Despite all his work to elevate the status of improvised music, trumpeter and composer Bill Dixon has been criminally underdocumented, appearing on just 24 records–in any capacity–in his 81 years. In 1964 Dixon helped galvanize the second wave of American free jazz by organizing the October Revolution in Jazz concerts and forming the short-lived but influential Jazz Composer’s Guild; he also taught at Bennington College for 27 years. He transformed his instrument’s language with his microtonal slurs, breath sounds, and long silences, and his use of these techniques in an orchestral setting on the landmark 1967 LP Intents and Purposes (RCA) still sounds like an unmet challenge today. On 2000’s Berlin Abbozzi (FMP) he demonstrates such dynamic control over his whispered cries and muffled explosions it’s as though he’s become the orchestra. For his Chicago debut, Dixon will be joined by local musicians Ken Vandermark, Michael Zerang, Nate McBride, and Josh Abrams. Tonight’s also closing night for Dixon’s first local exhibit of paintings, viewable from 4:30 to 7 PM at the Chicago City Arts Gallery, 410 S. Michigan, sixth floor. a 7:30 PM, Ganz Hall, Roosevelt University, 430 S. Michigan, 773-816-2336, $25. A –Bill Meyer