Lydian Dominant

Lydian with a flat seventh

The Lydian mode is 1 2 3 ♯4 5 6 7 — a major scale with a raised fourth, the open floating sound familiar from film music. Lower its seventh and the scale stops floating: the major third and flat seventh now form a tritone, which is what makes a chord a dominant.

So the alteration changes the scale's job entirely. Lydian belongs over a major seventh chord; Lydian dominant belongs over a dominant seventh, specifically one with a raised eleventh. The ♯4 that sounded suspended in Lydian becomes a colour tone in a chord that already wanted to move.

It is the only common scale that gives a dominant chord a natural thirteenth and a raised eleventh at the same time. Mixolydian has the natural thirteenth but a perfect fourth that clashes with the third; the altered scale has neither. That gap in the middle is the reason this mode is used.

The overtone scale

A second name for the same notes is the overtone or acoustic scale, and it comes from physics rather than theory. Harmonics eight through fourteen of a vibrating string, reduced into one octave, land on exactly this pattern — root, major second, major third, raised fourth, fifth, sixth, flat seventh.

That explains why the scale sounds settled despite containing a tritone. Its notes are the ones the overtone series produces on its own, so the ear hears them as belonging to the fundamental rather than as alterations of something else. The raised fourth in particular is close to the eleventh harmonic, which sits between our perfect and augmented fourth.

The name carries a caution as well. The acoustic version is not in equal temperament — the eleventh harmonic is noticeably flatter than the ♯4 on a piano, and the seventh harmonic flatter than the ♭7. What we play is a tempered approximation of a natural phenomenon, which is close enough to be useful and not close enough to be the same thing.

Where it is used

The everyday application is the tritone substitution. Replacing G7 with D♭7 in a two-five-one puts a dominant a tritone away from where the ear expects one, and Lydian dominant is the scale that fits it: the substitute chord's raised eleventh is the original chord's root, so the note that sounds most exotic is the one holding the two chords together.

It also covers the ♯11 dominant written explicitly in a chart, the second chord of a blues where the IV7 arrives early, and the whole vocabulary of Brazilian jazz harmony, where dominant chords with a raised eleventh are ordinary rather than a special effect.

On guitar the route is the same one that serves the whole family: play melodic minor a fifth below the chord root. Over D7♯11, play A melodic minor. Learning the parent scale in five positions covers this mode, the altered scale and Locrian ♮2 at once — the notes never change, only the chord underneath does.

Frequently asked questions