Neapolitan & Augmented Sixths

By now you know the dominant, the V chord, is the big tension chord that pulls home to the tonic. Composers found especially dramatic ways to lead into that V: rich, colorful chords whose whole job is to push hard into the dominant. Two families of them are the Neapolitan chord and the augmented sixth chords.

Both are setup chords, the kind that come right before the V and make its arrival feel strong and certain. They use notes from outside the key to make chromatic pulls, so they stand out from the chords around them. Think of them as extra-strong springboards into the dominant.

Play any chord, then a V chord, then home. Now imagine a richer, more colorful setup chord in that first spot, leaning hard into the V. That is what these chords do.

The extra pull these chords add is all in the voice leading. Where ii and IV approach the dominant with diatonic notes, the Neapolitan and augmented sixths alter one or more degrees so that voices slide into the dominant. They fill the same predominant slot, with a stronger chromatic pull.

Both families mainly serve one purpose: to make the arrival on the dominant more forceful. Each introduces chromatic tones that pull into the V chord: the augmented sixths by half step from both sides, the Neapolitan by its falling lowered second. Both belong in the predominant slot from the Chord Progressions class, between the tonic and the dominant.

The Neapolitan chord is a major chord built on a surprising note: the flatted second degree of the scale, the note just a half step above the home note. In the key of C, that gives a D-flat major chord. Because it is built on a note foreign to the key, it sounds dark and rich.

It almost always appears in first inversion, which puts the fourth degree of the scale in the bass and makes the chord flow smoothly, so it is usually called the Neapolitan sixth. It works as a strong setup chord, leaning toward the dominant and then home, and it is especially common in minor keys, where it gives the music a dramatic sound.

Play a D-flat major chord in the key of C, then move to the G chord and home. That lush, dark setup chord is the Neapolitan.

The Neapolitan draws its color from the lowered second degree, a note a half step above the tonic that belongs to neither the major nor the natural minor scale. Building a major triad on that flattened second produces a chord poised a semitone over the tonic, whose strangeness gives the Neapolitan its dark, faintly foreign sound, and whose lowered second degree drives the chord's resolution downward toward the dominant. In a major key the chord also borrows the lowered sixth, so it carries two notes from outside the key.

First inversion is standard because of the voice leading it produces. Placing the fourth scale degree in the bass lets the bass step smoothly up to the dominant, while above it the flatted sixth falls a half step to the fifth and the flatted second drops a diminished third down to the leading tone. The name links the chord to Naples, though where the name came from is not certain and the chord was used far beyond that city.

The augmented sixth chords are named after a special stretched interval hidden inside them. Two notes sit an augmented sixth apart, a hair wider than a normal sixth: the sixth note of the scale lowered and the fourth note raised (in C, A-flat and F-sharp). That stretched interval is tense and wants to expand. The two notes pull apart from each other, each moving a half step outward, until they arrive on the dominant an octave apart.

That outward push is the signature sound of these chords: two voices spreading apart by half steps to land on the V. It is why these chords sound so charged.

Picture two notes a stretched sixth apart, then imagine them spreading outward, each by a half step, to arrive on the dominant. That expansion is the augmented sixth resolving.

The augmented sixth interval is spelled the way it is because spelling encodes resolution. The same two pitches could be written as a minor seventh, but notating them as an augmented sixth, the lowered sixth degree beneath the raised fourth, records that both are leading tones aimed at the dominant, one from below and one from above. The notation captures a voice-leading intention that an enharmonic minor seventh would hide.

The chord's force comes from that double leading-tone pull. Two voices a half step on either side of the dominant resolve outward onto it at once, both landing on the fifth degree an octave apart, so an augmented sixth drives toward the dominant harder than a diatonic predominant does. The three types differ only by which note is added inside that interval.

The augmented sixth chords come in three flavors, named after countries: Italian, French, and German. All three contain the same stretched, outward-pulling interval; they differ only in one extra note added in the middle, which changes the color while keeping the same strong pull to the dominant.

The Italian is the plainest, with just three different notes. The French adds a note that gives it a sharper, more piercing sound. The German adds a note that makes it rich and full, so full that, played by itself, it sounds just like a dominant seventh chord. You do not need to memorize every note yet; just know that these are three shades of one setup chord.

Think of one strong springboard chord in three thicknesses: lean (Italian), bright (French), and full (German). All three launch into the dominant.

The three national types are thickenings of one underlying chord. All share the augmented sixth frame of lowered sixth and raised fourth around the tonic, and they differ only in the added note: the Italian adds nothing further, the French fills in the second degree, the German the lowered third. The added note tints the color, and the outward pull to the dominant stays the same in all three.

The German sixth has a second identity. Because it sounds like a dominant seventh, it can be respelled as the dominant of another key, which makes it a favorite hinge for enharmonic modulation to remote regions. Composers used that ambiguity to slip from one key into a distant one.

For all their richness, both the Neapolitan and the augmented sixth chords do the same simple job: they lead strongly into the dominant. Each is a colorful, chromatic setup chord placed just before the V, and each moves into that V with half-step motion, so the dominant, and then the final home chord, land with extra weight.

To spot them, listen for a chord with notes from outside the key right before a big cadence. If it is a major chord a half step above the tonic, it is likely a Neapolitan; if it has that stretched, outward-squeezing sound resolving onto the dominant, it is an augmented sixth. Both are signs that a strong cadence is coming.

Listen for a rich, dark chord just before the music leans into its tension chord. That colorful setup is often a Neapolitan or an augmented sixth.

Both lean into the dominant, though from different directions. The Neapolitan leads in with its lowered second degree falling to the leading tone, often through the tonic; the augmented sixths resolve outward onto the fifth from a half step on either side. Each replaces a plain diatonic predominant with a more chromatic one.

These chords round out the chromatic chords covered in this course. A secondary dominant tonicizes a chord, modal mixture recolors one, a modulation changes the key, and these chromatic predominants intensify the drive to the dominant. You usually meet the Neapolitan and augmented sixths right before a cadence, with one to three notes bent out of the key.