Musical modes

''This article is about modes as used in music. For other uses, see mode.''

Definition
Mode (from Latin modus, "measure, standard, manner, way") is a term from Western music theory having three senses :

(1) the rhythmic relationship between long and short values in the late medieval period;

(2) in early medieval theory, interval; and,

(3) most commonly, a concept involving scale and melody type (Powers 2001).

Beginning at the end of the eighteenth century, the term began to be used in ethnomusicological contexts to describe pitch structures in non-European musical cultures, sometimes with doubtful compatibility (Powers 2001 §V,1).

Mode and scale
In music, a "scale" is an ordered series of intervals, which, along with the key or tonic, define the pitches. However, "mode" is usually used in the sense of "scale" applied only to the specific diatonic scales found below.[citation needed]

Diatonic Modes
A mode can be viewed as an alternative ordering of an existing collection of pitches. For example, the 7 pitches contained in a key with 0 flats and 0 sharps (C major) can be ordered with C as the root to create the Ionian mode (C D E F G A B C), or with D as the root to create the Dorian mode (D E F G A B C D). In total, there are 7 different modes of the diatonic collection, which can be viewed as the major scale with the root changed to different scale degrees. The Ionian mode is more commonly known as the major scale, and the Aeolian mode is more commonly known as the minor scale (or the natural minor scale, as opposed to the harmonic and melodic minor scale, which are not modes of the major scale).

Non-Diatonic Modes
It is also possible to create modes out of scales that are non-diatonic, such as the ascending melodic minor scale or the harmonic minor scale. Especially in jazz, it's common to use the modes of melodic minor in junction with certain chord extensions/progressions that do not exist in the diatonic collection (for example, the Lydian Dominant mode is used frequently with a V7(#11) chord). Listed below are some of the more common non-diatonic modes, however modes can be made from any parent scale.

Relative Major Approach
A very common approach to learning modes in American music education is to learn modes as they relate to their relative major scale, the scale that shares the same pitches (i.e C Major and D Dorian). In this approach modes are constructed by taking the major scale and selecting different scale degrees as the root of the mode (i.e selecting the 2nd scale degree of the major scale as the root creates the Dorian mode, in C major the 2nd scale degree is D, so D Dorian has the same pitches as C major). This approach can be very useful when used in junction with chord scale theory, as the mode built off of a given scale degree is usually the mode paired with the chord built off of that same scale degree (i.e in C major, the ii chord is D minor, D Dorian (the 2nd mode of C major) is the mode that is commonly paired with that chord). This approach allows students who already know their major scales to learn other modes quickly, since each mode can be constructed using existing major scales (for example, to find B locrian, you find which major scale has B as the 7th scale degree (C Major) and order the pitches of that collection starting on B). It also helps students make connections between chords and modes (I-Ionian, ii-Dorian, V7-Mixolydian) when applying chord-scale theory, especially jazz students first learning to solo over chord changes.

Parallel Major Approach
Another approach is to learn modes as they relate to their parallel major scale, the scale that has the same root (i.e C Major and C Dorian). In this approach, modes are created by raising/lowering the scale degrees of the major scale, similar to the way that harmonic minor is created by raising the 7th scale degree of natural minor (note that harmonic minor is not a mode of the natural minor scale, it is its own scale entirely because that collection of intervals (W-H-W-W-H-m3-H) does not exist in any diatonic scale). A benefit to this approach is that it's easier to see the differences between Ionian/Aeolian and other modes to recognize their unique characteristics. Students can extrapolate changes to melodies and harmony by raising/lowering scale degrees from major. For example the third of a V chord is the 7th scale degree of a scale, in major the V chord is major (in C major, G B D), but in Mixolydian the v chord is minor (in C mixolydian, G Bb D) because the 7th scale degree is lowered by a half step. This is a useful approach when modes are utilized the same way keys are, where the harmony is built off of the scale and the 1st scale degree is largely tonicized, however it can also be a useful approach when modes are paired with chords, such as in chord-scale theory. All 7 of the Ionian modes can be expressed as alterations to scale degrees of the major scale, as shown below. Something potentially useful to keep in mind is that the change in pitches between modes (from Lydian to Ionian, from Ionian to Mixolydian, etc.) follows the circle of 5ths. Going through the circle clockwise raises pitches in modes (C lydian contains the same notes as G major, F is raised by a half step to F#) and going through the circle counterclockwise lowers pitches in modes (C Mixolydian contains the same notes as F major, B is lowered by a half step to Bb). If you know the order that pitches are raised/lowered in the circle of 5ths, you can find out which pitches in a given mode change. This also works for larger "leaps" between modes, (for example, C Dorian has 2 notes lowered from C Ioanian, the 2 notes that change when you move twice counterclockwise in the circle of 5ths are Bb and Eb, so C Dorian contains both Eb and Bb). This method may be helpful for students who have already learned their major scales through the circle of 5ths, and are moving on to learning diatonic modes.

Modality
"Modality" refers to the pitch relationships found in music using modes and contrasted with later tonality. The use of more than one mode makes music polymodal, such as with polymodal chromaticism. While all tonal music may technically be described as modal, music that is called modal often has less diatonic functionality and changes key less often than other music.[citation needed]