JAZZ PERSPECTIVES Jazz Forms - Evolution Of The Jam Session
For the first fifty years or so of jazz history the 12-bar blues and 32-bar song form dominated the jazz improviser's selections.
Although there were frequent departures from these simple forms, the jam sessions, in which new
musical ideas were forged and tested, consisted of them almost exclusively.
Steady and often rapid harmonic changes accompanied the traditional song
selections, and the jazz / swing feeling of four beats to the measure was always
On the album Kind of Blue, recorded in 1959, Miles Davis and his group began an in-depth exploration of an ancient type of harmony, never before used in jazz, called modal harmony. The musical result yields few or no chord changes, and no chords or melodic tones outside of the specific modal scale. In
Miles, The Autobiography [p. 225], Davis states, "The challenge here, when you work in the modal way, is to see how inventive you can become melodically. It's not like when you base stuff on chords, and you know at the end of thirty-two bars that the chords have run out and there's nothing to do but repeat what you've done with variations." Since harmony was no longer locked into measurable repetitive patterns, the necessity of set lengths for forms disappeared, leaving the soloist free to determine the phrasing.
Flamenco Sketches is one result of this concept. In the improvised sections the soloist moves through a set of modal
areas at a pace determined by them, and the band uses visual and auditory cues to follow along. In this way the form is developed spontaneously.
The rhythmic revolution leading to a new way of jamming was triggered in the fifties with the use of the jazz waltz, music with a three-beat measure. Dave Brubeck advanced this idea on
Time Out with the Paul Desmond composition Take Five, a song with five-beat measures. The melody is presented in an AABA format, but the improvisation takes place over an indeterminate repetition of the A section, a one-measure phrase with a two chord modal harmony pattern. John McLaughlin explored unusual divisions of time extensively in the sixties and seventies, on the albums
Extrapolation and My Goals Beyond, and with the Mahavishnu Orchestra. As a musician rooted in the blues, he created new rhythmic approaches to this form with
Binky's Beam in a 19-beat pattern, and Follow Your Heart in an 11-beat pattern. The title track of
Birds of Fire combines different patterns of 3, 6, and 9 to create a unified and interlocking groove for solos, with unusual harmonic and melodic approaches in a two-measure pattern.
The result of all of this evolution is jam sessions where the rhythm section sets up a
groove with a chosen time feel, and the form, melody and harmonic changes are spontaneously generated by consensus, listening and sensitive musical response. This is now just as common to the jazz jam as calling a standard tune or picking a key for a 12-bar blues. The jazz musician who wishes to stay current in music learns to create in all of these contexts, and many others. As the sphere of jazz knowledge and potential continues to expand, the frontier of improvisation increases exponentially.
- article by Frank Singer ©2002
I - Beginnings
II - Jazz and Technology
III - Radio and the Industrial Beat
I - Precursors
II - The Decade of Swing
III - The
First Look Back
The 32 bar Song Form
The Latin Influence
Evolution 1 - A New Dialogue
Evolution 2 - Into The Seventies
Evolution Of The Jam Session