The Neapolitan 6th Chord

Having explored the broad concept of the "pre-dominant" chord in the previous chapter, we can now look at two vitally important pre-dominant chords, the Neapolitan 6th and the Augmented 6th chords. This page covers the N6 type.

The Neapolitan 6th chord is an expressive alternative to the ii6 chord, and most often found in the minor key, although there are plenty of examples of it in major.

Its genesis is very simple. Take the progression iiº6 - V7 - i in a minor key, and use the lowered second degree of the scale for the supertonic triad.

Grasp this central point and you understand everything you need to know about the Neapolitan 6th. The rest is how it is spelled, how to work with it and how it is employed for use by composers.

What is unique about the Neapolitan 6th is the presence of the lowered second degree of the scale. In this way, the chord is also called called the "Phrygian II," although not in conversation. When discussing this chord in musical dialogue or in academic writing, the term Neapolitan still applies. Theoretically, however, it really is chord that comes from a Phrygian, lowered second modality.

What is unique about the Neapolitan 6th is that it seems to have a dual nature.

On one level, it is just what we have described: a ii chord in first inversion with a lowered second degree of the scale, which in this case means a lowered "root."

But the chord takes on its particularly expressive and poignant quality due to its actually sounding like a major triad in first inversion, rooted on the lowered second degree (the Phrygian second) of the scale. The note is found, in just intonation, by finding the reciprocal third of the reciprocal fifth:

Thus, the Neapolitan 6th chord takes on a strong reciprocal quality.

The dual nature of the N6 is expressed in this way: melodically, the lowered second has a tendency to fall directly to the tonic note (Db falls to C), and yet harmonically the chord is definitely a part of the "pre-dominant" family, since it is variation on a supertonic triad in first inversion, which has a strong tendency to move to V. The chord has both strong reciprocal energy and yet also points and functions as a pre-cursor to V.

Once the Neapolitan 6th chord became a common-use harmony, composers began to voice the chord even in root position, making the "flat II" quality, or the Phrygian quality, even stronger.

When analyzing this chord using Roman numerals, one can either use the N6 designation, refering to the term Neapolitan, or one can more formally use bII6. I prefer to use the N sign, which draws attention to its unique status in musical expression—"the Neapolitan harmony." However, the designation bII6 points to its Phrygian character. We'll use both interchangeably, so you are used to both ways of thinking.

Neapolitan 6th voice leading

In general, the inverted bass note, step 4 of the key, is the best note to double because it is the subdominant note of the key. Melodically, the lowered second is often voiced in the soprano. The chord either moves directly to V or is interrupted by a passing (or elongated) I6-4. Another common example, seen here in the final measures, is for the bass note of the N6 to rise a half step, creating a viiº7/V.

Musical Examples

Here is an example of a standard and yet highly expressive use of the Neapolitan 6th, from the Mozart Requiem. The passage is in A minor:

Notice how the lowered second appears in the melody, which is most expressive location for the altered Phrygian tone. The harmonic progression allows for a smooth parallel bass motion to the melody. The choir is singing quite forcefully here and this occurance of the N6 is quite dramatic.

Another famous, and quite different, expression of N6 occurs in Beethoven's Moonlight Sonata. The introductory bars, before the entrance of the plaintif melody, contains an impossible-to-miss D major triad in the context of a C# minor composition. Memorizing the sound of this opening is a good way to infuse the sound of Neapolitan in your ears.

Go to the Naxos site and give the Moonlight sonata a listen!

In your anthology, you can find the Chopin Prelude in C minor, with two intriguing instances of the Db Phyrgian harmony. At the opening, the Db chord, while reflecting the Phrygian II, actually transforms into a IV chord in the key of Ab major, the submediant. At the end of the piece, the same phrase, however, uses the identical chord as a Neapolitan 6th, cadencing in C minor. Be sure to look at this example in your anthology.

So commonplace did the Neapolitan (Phrygian) relationship become, that composers began to use the Neapolitan "Phrygian II" triad in extended passages. Beethoven's Appassionata Sonata, Op. 57, opens dramtically in F minor, followed by the same opening phrase re-stated immediately in Gb major. Startling! Chopin begins his G minor Ballade with an extended Ab major arpgeggio in the first four measures, thus emphacizing the Neapolitan chord even before getting around to voicing the tonic triad! A neat trick.

Go to the Naxos site and listen to the opening of the G minor Ballade. Can you hear the Neapolitan opening?

Thus, one will often, then, speak of  "Neapolitan" relationship in a piece of music, meaning a relationship between the tonic key and the key or harmony that is the lowered second degree of the scale. Thus, "Neopolitan" has become synonymous with "flat two" or "lowered second degree" or "Phrygian harmony."

Conclusion

It is important, and helpful, to know that the N6 chord was born from the seedbed of the supertonic triad in first inversion. The N6 is the darker, reciprocal, earthier cousin to the iiº6. Once born, it went on to live a productive and creative life of its own, ultimately proud and happy to be voiced with its "errant" flat two strongly in the bass voice. Why not?

NEXT: 6C: The Augmented Sixth Chords.

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