Mixture – bII or Neapolitan-Function

Definition: The bII, Neapolitan, or Phrygian II chord is a major triad built on the lowered 2nd (b2) scale degree. It is called Phrygian II since it is occurs naturally in the Phrygian mode.

Function of the bII, Phrygian II, Neapolitan

Being a variant of a II chord, the bII or Neapolitan acts as a supertonic and therefore, functions as a pre-dominant chord.

As a pre-dominant chord, the bII chord normally resolves/moves to dominant.

In Sicilienne, the bII, marked as a N (Neapolitan), does go to V.

Note several things in the above example:

The bII chord or Neapolitan is usually found in first inversion.

In the above example, a N6 (Neapolitan in first inversion) is used, not a root position chord. If a root position chord were used, the bass would go from Db to G which is an Augmented 4th or tritone. This skip is usually avoided melodically since it is difficult to sing. By putting the chord in first inversion, the bass moves from F to G – a much smoother movement.

The Neapolitan is so often found in first inversion that it is often called the Neapolitan sixth chord.

The third of the bII or Neapolitan chord is usually doubled.

The overall rule of doubling is to double the stable tone of the chord. The most stable note of this chord is the third (in this case, the F, the 4th scale degree) since it is the only unaltered note and the subdominant (4ths scale degree, one of the primary tones) of the key.

Resolving the bII or Neapolitan

Below is a simple SATB version of a bII resolving directly to a V7 chord.

In the above progression, we see several things that have been noted above:

The chord appears in first inversion.

The third of the chord is doubled.

In addition, we notice that there is a d3 interval in the soprano between scale degree b2 and 7 (Db and the B-natural). Even though diminished intervals are usually avoided melodically,

the diminished third melodic interval is the distinctive interval of the N6 to V progression and is therefore permitted.

It is actually desired to have the d3 present and even emphasized by being placed in the soprano voice.

If the d3 interval is not desired, then the bII6 chord should resolve to a V(7) via a cadential 64 chord (which is still a dominant function), as shown below:

By going to the cadential 64, the interval of the d3 (b2 to 7) is filled in by the tonic note of the 64 chord.

Hint: If you are going from the bII to the cadential 64, be careful to keep the b2 scale degree above the b6 scale degree in the bII chord otherwise you will have parallel 5ths.