Audio: modal jazz (0:08)
modal jazz plays modal jazz by a piano and violin. The modal jazz figure shows the score:
Modal jazz is the use of modes in jazz harmony.
The seven modes are used to write modal jazz. There is no precedence among them. The ionian, the major scale, is on a par with all the other modes.
There are no new chords in modal jazz, as explained in the chapter on modal harmony. A modal jazz chord is a normal tertian chord constructed in thirds.
Chord notation is a small but important issue in modal jazz. It is OK to use a chord name or number or both together, but a chord name has advantages over Roman numerals. The chord, Cmaj7, for example, contains the notes CEGB. It is the tonic chord in the keys of C major and C lydian and numbered Imaj7. It is chromatic in the rest of the modes. The use of a chord number implies a key, the use of a chord name does not. Naming a chord and omitting the number seems to be more in the spirit of modal jazz. It also avoids the need to describe a chord as diatonic or chromatic.
A chord name provides a clue to mode. For example, the chord Cmaj13 is a clue that the key is C major or one of its related modes. The chord, Cmaj13#11, might look unusual at first sight, but it is a clue that the key is C lydian or one of its related modes. A thirteenth chord scored in full provides a clear indication of key. For the purpose of modal jazz performance, it is more common to write smaller chords, even triads, to allow the performer discretion to improvise over that chord in whichever mode(s) they choose.
There is no obvious mechanism for writing a modal jazz progression. There is no driver of a chord progression in the traditional sense that a key drives chords. In modal jazz, key is passive, because the mode can and does change with each chord. Chords do not form a progression in a single key, they form a succession in many possible modes. A modal jazz progression is largely a series of pleasant or interesting sounds.
It is probably best to regard the choice of chords in a progression as solely at the discretion of the composer. It is still possible to write familiar progressions, such as ii-V-I, it is simply that the progression will be interpreted as a succession of chords in different modes rather than as a progression of related chords in a single key. Take the ii-V-I progression, Dm-G-C, as an example. In jazz harmony this has so far been treated as a progression of three related chords in the key of C major. In modal jazz, the Dm chord could represent vi in the key of F lydian, the G chord could be V in C# locrian, and the C chord could be I in C mixolydian. It may seem unnecessarily complicated to treat ii-V-I as modal modulation but that is the way it is in modal jazz.
Modal jazz refers to a style of jazz as much as it does to an approach to jazz harmony. The style is characterised by the use of a few chords, usually quite simple in nature, and with a long duration. Melody is improvised over each chord using different modes. Variety is achieved by changing the mode used to melodise a chord rather than by changing the chords in a progression. The key naturally changes with each mode change.
In all the different approaches to harmony thus far, a chord has been treated as belonging to a key. The notes that make up the scale in a key are the notes that are used to construct chords such as triads, seventh chords and extended chords. Modal jazz turns the notion of key on its head. Instead of a chord belonging to a key, a key belongs to a chord. A chord becomes an entity in its own right. The notes it contains can belong to one key, or two keys, or multiple keys.