Editing Jazz scale (section)

== Theory ==
{{Image frame|content=<score sound="1">
{
\override Score.TimeSignature #'stencil = ##f
\relative c'' {
  \clef treble
  \time 6/4 g4^\markup { "G whole tone scale" } a b cis dis f \time 4/4 g1 \bar "||"
  \time 4/4 <g, b des f>1 \bar "||"
} }
</score>

<score sound="1">
{
\override Score.TimeSignature #'stencil = ##f
\relative c'' {
  \clef treble
  \time 8/4 g4^\markup { "G octatonic scale" } gis ais b cis d e f \time 4/4 g1 \bar "||"
  \time 4/4 <g, b des f>1 \bar "||"
} }
</score>

<score sound="1">
{
\override Score.TimeSignature #'stencil = ##f
\relative c'' {
  \clef treble
  \time 7/4 g4^\markup { "4th mode of D melodic minor scale" } a b cis d e f \time 4/4 g1 \bar "||"
  \time 4/4 <g, b des f>1 \bar "||"
} }
</score>

<score sound="1">
{
\override Score.TimeSignature #'stencil = ##f
\relative c'' {
  \clef treble
  \time 7/4 g4^\markup { "7th mode of A♭ melodic minor scale" } aes bes ces des es f \time 4/4 g1 \bar "||"
  \time 4/4 <g, b des f>1 \bar "||"
} }
</score>
|width=340|caption=Four scales compatible with G<sup>7{{music|flat}}5</sup>}}
One important feature of jazz is what theorists call "the principles of [[Chord-scale system|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 [[ii–V–I turnaround|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 [[Altered chord|alter]] the V chord, G<sup>7</sup> (G–B–D–F), with a [[Dominant seventh flat five chord|flattened fifth]], producing the chord G<sup>7{{music|flat}}5</sup> (G–B–D{{music|flat}}–F). An improviser might then choose a scale containing these four notes, such as the G whole tone scale, the G octatonic scale, or a mode of either D or A{{music|flat}} melodic minor ascending. In each case, the scale contains the chord tones G–B–D{{music|flat}}–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 [[Consonance and dissonance|dissonant]] to be emphasised against the underlying chord, and so is either avoided, used as a passing tone or chromatically altered.<ref>{{cite book |last=Humphries |first=Carl |title=The Piano Handbook |publisher=Backbeat |year=2002 |pages=262 |isbn=0-87930-727-7}}</ref> For example, in major-key harmony the 4th, and thus the 11th, is an avoid note and is therefore either treated as a passing tone or is augmented (raised a semitone).<ref>Humphries (2002), p. 128.</ref> Avoid notes are often a minor second (or a minor ninth) above a chord tone<ref>{{cite book|last=Nettles|first=Barrie|title=Harmony 1|year=1987|publisher=Berklee College of Music|page=34}}{{Full citation needed|date=July 2015|reason=Place of publication, ISBN needed.}}</ref> or a perfect fourth above the root of the chord.<ref name="Humphries 126">Humphries (2002), p. 126.</ref>

<blockquote>[One] 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 ["what is sometimes called an avoid-note"] (because it's ''really'' dissonant), meaning that all the others are okay.<ref name="Humphries 126"/></blockquote>