Modal Jazz - Theory

Theory

It is possible for the bassist and the pianist to move to notes within the mode that are dissonant with the prime (tonic) chord of that mode. For example: within the C ionian mode, the notes of the scale are CDEFGAB, with C being the root note. Other non-diatonic notes, such as the note B♭, are dissonant within the C ionian mode, so that they are less used in non-modal jazz songs when playing the chord C. In a modal song, these other notes may be freely used as long as the overall sound of C ionian is entrenched within the listener's mind. This allows for greater harmonic flexibility and some very interesting harmonic possibilities.

Among the significant compositions of modal jazz were "So What" by Miles Davis and "Impressions" by John Coltrane. "So What" and "Impressions" follow the same AABA song form and were in D Dorian for the A sections and modulated a half step up to E-flat Dorian for the B section. The Dorian mode is the natural minor scale with a raised sixth. Other compositions include Davis' "Flamenco Sketches", Bill Evans' "Peace Piece", and Shorter's "Footprints".

In improvising within a modal context, a musician would start by thinking about playing the notes within that specific mode (e.g., D Dorian: D, E, F, G, A, B, C, D). It is also possible to take several notes from that mode (though not all) to create smaller scales or note choices for improvisation. For example, in D Dorian, one may play the notes of the D minor triad. This is what Miles Davis does at the beginning of his solo in "So What". The player may even choose any of the triads available in that mode: C major, D minor, E minor etc. One thing to note is that choosing an upper structure triad using the 9th, 11th and 13th of the chord will result in tension.

The bassist, in a modal context, is not required to 'walk' from one important chord tone to that of another in order to make each chord change sound, in the same way required in conventional bebop or hard bop compositions; rather, he or she is free to improvise bass lines that may highlight or emphasize particular scale degrees within a specific mode (e.g., a bass line that is constructed to highlight the 6th degree during a Dorian chord). As a result, bass lines found in modal jazz are often constructed in four or eight bar phrases with an emphasis of the root or fifth degree on beat one of such phrases. Similarly, the comping instrument is not confined to play the standard chord voicings of the bop lexicon, but rather can play chord voicings based upon differing pitch combinations from the parent mode.

The way soloists created solos changed dramatically with the advent of modal jazz. In bebop, a soloist typically constructs solos to fit within a particular set of chord changes. In modal jazz, with its lack of conventional bop chord changes, the soloist can create interest by exploring the particular mode in rhythmically and melodically varied ways. Modal jazz is, in a sense, a return to melody.

The player may also use the many different pentatonic scales within the scale such as C minor pentatonic, F major pentatonic and G minor pentatonic. Note that these scales are also relative E♭ major, D minor and B♭ major pentatonic, respectively.