FREE JAZZ, the new thing, Great Black Music. Call it what you will, no organization has had such a profound impact on the shape of jazz in the past 17 years as Chicago's Association for the Advancement of Creative Music.

As a collective whose original purpose was not only to promote creative music but to sustain the jazz tradition and to enhance the quality of life of its members, the AACM proved to be a powerful and persuasive force, no more so than in the late '70s when free jazz and the loft scene flourished in New York City. As a source of pride and inspiration, AACM's presence continues to be felt in the work of some of its most gifted alumni, a number of whom have issued new albums.

With the release of "Urban Bushmen" (ECM 2 1212), the Art Ensemble of Chicago has finally received its due: a double record set that comes as close as one could reasonably expect to capturing the essence of these five musicians in concert.

The recording, made in Europe in 1980, isn't perfect; the pacing is off sometimes and the choice of material doesn't always reflect the band's best work. But more than any other AEC live set, this one capitalizes on the group's collective strength.

The first real indication of this is Joseph Jarman's "Theme for SCO." Marches being a hallmark of the AACM tradition, the ensemble falls into comfortable formation behind trumpeter Lester Bowie. In one of his few charmingly garrulous moments on the album, Bowie mixes cavalry charges and flamenco flourishes as he leads the ensemble into a tumultuous and exhausting free jazz blowout, one that ultimately tests the mettle and reflexes of each player.

Another highlight is Bowie's "New York Is Full of Lonely People," warmly sensitive yet all too brief. Then, too, there is the marvelous combination of bassist Malachi Favors Maghostut and percussionist Famoudou Don Moye. The other members of the ensemble--Bowie, reedmen Joseph Jarman and Roscoe Mitchell--are occasionally heard to better advantage elsewhere but the tandem play alone of Favors and Moye makes this album worth owning.

Anthony Braxton, the AACM's most famous son, has released "Six Compositions: Quartet" (Antilles AN 1005). In any context, Braxton's compositions belie the idea that post-Coleman jazz is unstructured and undisciplined. Above all else, Braxton is a composer and the pieces he's included on this album, all written in the mid to late '70s, readily reveal his involvement in a number of areas.

One piece, the album's opening track, is a refreshingly swinging post bebop tribute to saxophonist Lou Donaldson. In contrast to the often jagged staccato edge of his solo pieces, Braxton's playing is more linear and agile, a response in part to the exceptional rhythm section he's assembled for this session--pianist Anthony Davis, bassist Mark Helias and drummer Ed Blackwell.

More experimental forms are pursued elsewhere. On one piece, Braxton imposes structure by providing the quartet with a dozen six-note figures to choose from in the heat of improvisation. On another, a 16-note scale, heard as an elongated bass ostinato, guides the ensemble. Still another provides the musicians with specific thematic choices from which to launch open improvisations. In every case the quartet is equal to these challenges and the results are often revealing.

Intentional or not, "Six Compositions" turns out to be a fine sampler of Braxton's work, bridging as it does some of his older "In the Tradition" recordings with his more inquisitive side.

Finally, of all the musicians fostered by the AACM, the members of Air are perhaps best capable of striking a balance between creative and traditional forces, between an adventurous spirit and an accessible sound. The best example of this approach was found on the much-acclaimed album "Air Lore." Released a few years ago, it brought new excitement to the works of Scott Joplin and Jelly Roll Morton.

In the view of Henry Threadgill, the trio's alto saxophonist and principal composer, Joplin and Morton's music is not archival material reserved solely for faithful and reverent interpretation: To Threadgill, this is music that lives and breathes and, above all, inspires.

Air's new album, "80 Below 82" (Antilles AN 1007), picks up where "Air Lore" left off with an anything-but-academic treatment of Morton's "Chicago Breakdown." As the tune unfolds, the trio first appears to be working at cross purposes, Threadgill slowly navigating his way around the rhythm section. But soon Morton's theme emerges--a jaunty melodic figure as inviting as ragtime itself. From there, the trio uses the theme as a springboard to improvisation, beginning with bassist Fred Hopkins' darkly probing lines and moving through Threadgill's expansive and increasingly ragtime inflected candenza.

Apart from Morton's contribution, Threadgill's "Do Tell" is the album's most memorable selection and certainly the one most typical of how these musicians collaborate. Again the theme is all important; this time it's more an earthy R&B figure delivered by Threadgill in a breathy fashion. By the tune's end, Hopkins carries the theme, but in between there are many cathartic moments of tension and release and little of the randomness often associated with free jazz.

In fact, what makes Air's music so accessible is that Threadgill seldom violates the inherent limitations of the saxophone and his compositions favor relatively conventional harmony. The surprises, the motion, the excitement comes in hearing the trio develop a truly democratic and conversational approach to jazz, a jazz in which shifts of time and texture play a significant role.