What are the seven modes?
Play the white keys from C to C and you hear C major. Play them from D to D and you hear something else: the same seven keys with a different home note. That is a mode. A major scale has seven notes, so it offers seven starting points, and each one has a name of its own.
There are two ways to keep a mode in your head. By rotation, it is the white keys played from a different starting key. By comparison, it is a major scale on the same home note with a few notes lowered or raised: C Dorian is C major with the 3rd and 7th lowered. Musicians reach for the second view more often, because it tells you exactly what changes.
| Mode | White keys from | Against major, same tonic | 7th chord on C | What gives it color |
|---|---|---|---|---|
| Ionian | C | Same as major | Cmaj7 | The plain major scale |
| Dorian | D | ♭3, ♭7 | Cm7 | A major 6th inside a minor sound |
| Phrygian | E | ♭2, ♭3, ♭6, ♭7 | Cm7 | The ♭2, a half step above home |
| Lydian | F | ♯4 | Cmaj7 | The raised 4th |
| Mixolydian | G | ♭7 | C7 | A lowered 7th in a major sound |
| Aeolian | A | ♭3, ♭6, ♭7 | Cm7 | The natural minor scale |
| Locrian | B | ♭2, ♭3, ♭5, ♭6, ♭7 | Cm7♭5 | The ♭5: no steady fifth to rest on |
How do the modes sound different from each other?
Sort them by the third and you get two families. Ionian, Lydian and Mixolydian have a major 3rd and sound major. Dorian, Phrygian, Aeolian and Locrian have a minor 3rd and sound minor. Sort them from bright to dark and each step lowers exactly one note by a half step: Lydian, Ionian, Mixolydian, Dorian, Aeolian, Phrygian, Locrian.
Where do modes show up in today’s music?
Two places matter to a keyboard player. The first is the vamp, a groove that stays on one or two chords. A minor 7th chord that visits the chord a fourth above it (Dm7, then G7) suggests Dorian; a dominant 7th that visits the chord a whole step below it (C7, then B♭) suggests Mixolydian. The second is the chord-scale, the scale that goes with one chord. Which scale depends on the chord’s place in the key: over a minor 7th, Dorian on ii7, Phrygian on iii7, Aeolian on vi7, and Dorian or Aeolian on a minor key’s own i7; Mixolydian over a plain dominant 7th; Ionian or Lydian over a major 7th; Locrian over a half-diminished 7th.
What are the lydian dominant, altered and half-whole diminished scales?
The seven modes fit plain chords. A dominant seventh with a color named in its symbol takes one of three further scales. Lydian dominant is Mixolydian with a raised 4th (it is also the fourth mode of the melodic minor scale). Altered raises or lowers every note of a dominant that can move, the 9th, 5th and 13th (it is the seventh mode of the melodic minor). Half-whole diminished alternates half steps and whole steps, beginning with a half step, so it repeats every minor third. Here are the three on G, the dominant of C.
| Scale | Notes on G | Chord it goes over | What it gives the chord |
|---|---|---|---|
| Lydian dominant | G A B C♯ D E F | G7♯11 | The raised 4th (the ♯11) replaces the plain 4th, which sits a half step above the chord’s 3rd |
| Altered | G A♭ B♭ B D♭ E♭ F | G7alt | Every alteration at once: A♭ (♭9), B♭ (♯9), D♭ (♭5) and E♭ (♭13), the tensest dominant |
| Half-whole diminished | G A♭ B♭ B D♭ D E F | G7♭9 | Both ninths (A♭ and B♭), the 13th (E) and the ♭5 (D♭), with the 5th (D) kept |
The chord decides which one. A 7♯11 takes lydian dominant, and so do two dominants that do not resolve down a fifth: the tritone substitute (D♭7 in C), which takes only that, and the backdoor dominant (B♭7 in C), where Mixolydian also works. A plain I7 or IV7, as in the blues, takes Mixolydian first. A 7alt takes altered. A 7♭9 takes half-whole diminished, though altered is a common answer too, since many players reach for it when the chord leads to a minor chord. A maj7♯11 takes Lydian, the major scale with its 4th raised. The chord symbol harmony practice asks for these chords at level 6.