I did not initially overlook Ornette Coleman’s music; rather I decided that because his music was, strictly speaking, not “free improvisation”, that I ought not include it in this series. However, I have decided otherwise, given the powerful influence of his ideas which led (in part) to free improvisation being explored by jazz musicians in the 1960's.
Ornette Coleman. Photo from breath of life.
In his small group work, Coleman has used the head-solo-head paradigm which originated in small group jazz in the 1930's or so. In this idiom, the harmonic progression outlined by the melody was also to be outlined by the soloists in their improvisations. Coleman used this idiom as well (many tunes on Tomorrow is the Question are altered blues or rhythm changes forms, and the solos follow the traditional forms) but more often he diverged from it, allowing the soloist to follow her own harmonic progression.
Improvisation can follow a chord progression with no set form, (see Miles Davis' “Flamenco Sketches”, “Teo” and “Spanish Key”) or form with no set chord progression (some of Tristano's and Dolphy's more-outside improvisations are examples of this). But in general, Coleman's music excised both. This apparently simple innovation provided a great deal of insight into the role of the accompanying musicians as well, and by extension, the nature of the interplay between soloist and accompanist(s). If we are to maintain the traditional jazz value of mutual “listening”, then two options for interplay emerge: 1. the soloist/accompaniment roles are preserved, and the accompaniment leaps into a state of hyper-intense listening, or 2. the soloist/accompaniment roles simply collapse and the group arrives at collective improvisation.
It's important to emphasize that 2. does not mean free improvisation, nor does Coleman see it that way. The fact that the improvisation is free from the harmonic rhythm of the melody does not imply that the improvisation is completely independent of the composition. (If it were, then why bother playing a melody at all?) So in Coleman's music, the melody sets the tone; the improvisations which follow draw from bits and pieces of the melody. (I speculate that this is also the basic idea behind Cecil Taylor's “unit structures” theory of improvisation.)
Coleman’s string of highly influential Atlantic recordings in the late 1950’s set off what would become a firestorm of controversy and experimenting. Coleman was to jazz musicians what Marx was to economists, or what Gödel was to logicians: although he disrupted the established order, he was actually right in his general theory. Therefore he couldn't be ignored. Jazz musicians were always searching for ways to feel more freedom in improvisation, and Coleman certainly did this. By the early- to mid-60's, a large community of musicians in New York and elsewhere were busily testing the boundaries of jazz composition and improvisation. (Even mainstream figures like John Coltrane and Miles Davis were using Coleman's head-free solos-head idiom.)
Did Coleman play free improvisation? Probably. But I'm not aware of any recorded evidence from this early period.