Analyze and listen to the following short progressions. There are three progressions in major and then three similar progressions in the parallel minor. Start your analysis with leadsheet symbols and then provide Roman numerals. (You may want to refer back to Unit 17a to review the finer points of using the Roman numeral system.) In each progression below, there is a chromatic chord that will stand out. What is its function in each case? (e.g. tonic, passing, etc.) If you were to compare it to a diatonic or chromatic chord that normally fulfills this function, which chord shares the most commonalities with it? (Hint: Think about the inversion and choice of doubled notes.) Does it seem most “at home” in major or minor?
As you labeled the chords, you probably noticed that you had a chord that could only be explained as the borrowed II chord from the Phrygian mode. In each case, it was acting as a pre-dominant chord and followed the rules of a standard ii chord. This bII chord is used often enough that it earned a special name: the Neapolitan chord. The origin of the chord’s moniker (Neapolitan) is disputed, but recently, one could make a case for calling this the “Batman” chord; it has been featured prominently in almost every modern Batman theme. Composers love to use this chord to add darkness to a progression.
You may label the Neapolitan chord using standard Roman numeral notation (bII) as discussed in the mode mixture unit (Unit 17a), but it is also common to substitute an upper-case “N”–short for Neapolitan–in your Roman numerals. For voice-leading purposes, the chord may sometimes have an enharmonically equivalent pitch–such as the G# shown in the third and sixth progressions–but we still always analyze this as a bII chord.
The above examples are three of the most common ways in which you should approach and leave a Neapolitan chord:
As you observed in the example, the bII chord is most commonly used as a pre-dominant function. In this case, you can make the argument that it is most similar to a pre-dominant ii chord, because it has the same scale degrees of ^2, ^4, and ^6, with a lowered ^2 and ^6. While this is true, if you look at the common doubling and inversion of the Neapolitan chord–first inversion with a doubled third–it may be easier for you to consider the Neapolitan as a functional substitution for a borrowed iv chord. This ensures correct doubling and voice-leading tendencies. Look at the chords side-by-side in below, and you will notice there is only a half-step difference between the two chords.
Perhaps the most important reason for this doubling is that it solves two major part writing errors that occur for root-position bII chords:
You may use a Neapolitan chord as a pre-dominant function in any progression in which you could use a minor iv chord. In minor, there is only one chromatic pitch (^b2), but in major, you will need to lower both ^2 and ^6.
In the modal interchange video from Unit 17b, you may have noticed that one of the progressions used a bII chord. In the same unit, we then looked at a similar usage of the bII in the excerpt from Mahler Symphony No. 2. Let’s look at this again to refresh the details of your final analysis. How is the Neapolitan chord different from the above examples? What is its function here? If it is not a pre-dominant as above, then what chord from this new function shares the most commonalities with it?
As we discussed in 17b, in this case, the bII is acting as a functional substitution for a dominant function (or possibly a plagal cadential function). It shares many common tones with a viio7 chord, and these tendency tones follow the voice-leading resolutions that you would expect of a viio7. When it is used to resolve to a I chord, the voice-leading issues are difficult to overcome, so you must be thoughtful in your approach and resolution.
Please note: While the Neapolitan is a commonly used chord, it is far more common to use it as a predominant function rather than as a functional substitution for dominant. Remember that if you ignore the standard tonic/dominant relationship too often, the listener will begin to lose the sense of diatonic progression. This can be good or bad depending on your desired outcome.
As always, if you study a chord’s voice-leading, you can use this to deduce its function.