Neapolitan sixth chord

What it means

The Neapolitan sixth chord is a major triad on the lowered second degree, usually standing in first inversion, that is, with the third in the bass. In C minor it consists of F, A♭, and D♭, with F in the bass. In terms of function theory it is interpreted as a subdominant with an added minor sixth in place of the fifth and is designated with a sign of its own; roman-numeral analysis gives it as the lowered second degree.

Musical use

Its position in the cadence is fixed: it stands where the subdominant would otherwise stand and leads to the dominant, often by way of a cadential six-four suspension. Especially characteristic is the voice leading of the lowered note — in C minor, D♭ — which is usually led downward through C to the leading tone B. Between D♭ and B there lies a diminished third, an interval that gives the turn its peculiar colouring.

The effect is a sudden darkening or clouding immediately before the close. The sonority is most common in minor but also occurs in major, where it seems even more foreign.

The name goes back to the operatic school that was associated with Naples in the eighteenth century, in whose circle the sonority frequently appears; it was not invented there, however — it is found earlier still.

It is to be distinguished from the Phrygian sonority, which likewise contains the lowered second degree but there belongs to the scale and prepares no dominant.

In minor it often stands before the cadential six-four chord. Its effect rests on the flat-altered second note, which strives downward as a leading tone to the tonic or to the leading tone. In function theory it is usually designated sN, as a minor subdominant with a minor sixth instead of a fifth.

Performance practice

Lead the lowered note downward and give it weight as you do so — it carries the effect. Take a moment before the dominant, instead of hurrying through. And intonate the diminished third deliberately narrow; it is the core of the turn.