Jazz Scale

A jazz scale is any musical scale used in jazz. Many "jazz scales" are common scales drawn from Western European classical music, including the diatonic, whole-tone, octatonic (or diminished), and the modes of the ascending melodic minor. All of these scales were commonly used by late nineteenth and early twentieth-century composers such as Rimsky-Korsakov, Debussy, Ravel and Stravinsky, often in ways that directly anticipate jazz practice. Some jazz scales, such as the bebop scales, add additional chromatic passing tones to the familiar diatonic scales.

One important feature of jazz is what theorists call "the principles of chord-scale compatibility": the idea that a sequence of chords will generate a sequence of compatible scales. In classical major-mode harmony, chords typically belong to the same scale. (For example, a I-ii-V-I progression in C major will typically use only the notes of the C diatonic collection.) In jazz, a four-chord progression may use four different scales, often as the result of chordal alterations. For instance, in C major, a jazz musician may alter the V chord G-B-D-F with a flattened fifth, producing G-B-D♭-F. An improviser might then choose a scale containing these four notes, such as G whole tone (G-A-B-C♯-D♯-F), G octatonic (G-A♭-B♭-B-C♯-D-E-F), or a mode of either D or A♭ melodic minor ascending (G-A-B-C♯-D-E-F or G-A♭-B♭-C♭-D♭-E♭-F respectively). In each case the scale contains the chord tones G-B-D♭-F and is said to be compatible with it. This notion of "chord scale compatibility" marks a fundamental difference between jazz harmony and traditional classical practice.

An avoid note is a note in a jazz scale that is considered, in jazz theory and practice, too dissonant to be played against the underlying chord, and so is either avoided or chromatically altered. For example, in major-key harmony the fourth, and thus 11th, is an avoid note and thus either treated as a passing tone or augmented (raised a semitone). Avoid notes are often a minor second (or a minor ninth) above another note or a perfect fourth above the root of the chord.

can get a good sense of the difference between classical and non-classical harmony from looking at how they deal with dissonances. Classical treats all notes that don't belong to the chord (i.e., the triad) as potential dissonances to be resolved. ... Non-classical harmony just tells you which note in the scale to avoid (because it's really dissonant), meaning that all the others are okay.