III. Modulation and Chromatic Harmony
Composers tend to put considerable emphasis on harmonies leading to V. They apply noteworthy creativity in shaping and modifying those harmonies as a way of highlighting the arrival of the dominant, after which the tonic soon follows as a foregone conclusion. In addition to diatonic pre-dominant harmonies such as ii and IV (iio and iv in minor), applied chords can appear before the dominant, emphasizing it through tonicization (see Chapter 27). Other harmonies, like the Neapolitan sixth (Chapter 31) and augmented sixth chords (Chapter 32), dramatize the arrival of the dominant with chromaticism.
All of these chords and sonorities have a similar function in that they typically introduce and raise anticipation for dominant harmony. Though they share certain characteristics in makeup and purpose, each has a unique identity. The subtle differences between these chords allow for a wide variety of expression and individuality in works with fundamentally similar harmonic structure.
We introduced the pre-dominant function in Chapter 24. In this short chapter, we will summarize the various pre-dominant chords discussed so far. We will compare them and track the elements that most regularly appear in pre-dominants, while making note of the characteristics that make each unique.
33.2 Pre-dominant chords with diatonic 4
In discussing the commonalities and differences between various pre-dominant chords, it is useful to divide the list into diatonic chords—those built exclusively of pitches native to the key—and chromatic chords—those that contain pitches foreign to the key, whether through mixture or other sources. Among the scale degrees comprising various pre-dominant chords, 4 is central. In this and the following sections we will take a more nuanced approach to classifying pre-dominants. We will first discuss those pre-dominants that use diatonic 4, and then those that replace 4 with #4.
As discussed in Chapter 24, the most common pre-dominant chords are those composed of diatonic pitches: iio(7) and IV(7) in major, iio(7) and iv(7) in minor. Recall, too, that chords built on scale degree 2 regularly appear with the third in the bass, particularly in minor keys where the inversion helps conceal the tritone between 2 and 6. Notice the similarities between all four of these chords:
These chords all have scale degrees 4 and 6 in common, making them particularly useful as pre-dominants since these tones lead smoothly to the pitches of V or V7:
As discussed in Chapter 29, mixture chords typically retain the harmonic functions of their unaltered forms. In other words, a pre-dominant harmony that incorporates tones borrowed from the parallel key will still be pre-dominant. The following example alters the IV chord of Example 33–2:
Despite the inclusion of Ab, the iv chord retains a clear pre-dominant function.
The Neapolitan chord also has a pre-dominant function. Like ii or IV, it too has diatonic 4 (usually in the bass). As discussed in Chapter 31, the Neapolitan can be derived in two ways: by substituting the fifth of a iv chord with a chromatic upper neighbor or by lowering the root of a iio chord. The following example replaces the pre-dominant chords of Examples 33–2 and 33–3 with a Neapolitan:
Compare Example 33–5 with Examples 33–2 and 33–3. As you can see, the Neapolitan is closely-related to diatonic ii and IV chords. Regardless of how it is derived—whether by embellishing a iv chord, or by altering a iio chord—the Neapolitan retains pre-dominant function.
33.4 Pre-dominant chords with #4
Other pre-dominant chords, such as applied chords and augmented sixths, feature #4. As discussed elsewhere, #4 often functions as a temporary leading tone and urges strongly toward 5. The presence of #4 in a predominant chord makes it less stable and drives it toward the dominant.
As discussed in Chapter 27, applied chords that tonicize the dominant can be thought of as chromatically altered ii or IV chords. The following example demonstrates:
Here we see a diatonic pre-dominant (ii) leading to an applied chord (V/V). The only difference between these chords is at scale degree 4: raising F to F# makes an applied dominant out of the ii chord. (Note that the same progression in minor would require two accidentals to make an applied dominant out of the diminished iio chord.) Any applied chord tonicizing V—V7/V, viio/V, viio7/V, and so on—can be derived in this manner. Again, the similarity in makeup is responsible for the similar function.
Augmented sixth chords, as discussed in Chapter 32, are defined by the “dual leading tones” surrounding scale degree 5: #4 and b6.
Like applied dominants, they feature leading-tone chromaticism (#4 invariably resolves to 5). But the presence of b6 (a semitone above the dominant) prevents them from being heard as applied dominants. Augmented sixth sonorities, as chromatic pre-dominants, highlight the arrival of the dominant but do not tonicize it.
In this sense, augmented sixths may be regarded as further alterations of diatonic pre-dominants. Applied chords add #4 and augmented sixths add b6 in addition. The increased chromaticism enhances the pre-dominant function rather than undermining or changing it.
Diatonic ii (iio) and IV (iv) chords (and their respective seventh-chord versions) are the most common pre-dominant harmonies. Neapolitan chords and can be thought of as chromatic alterations of ii or IV chords. They also contain 4 and retain pre-dominant function.
Other pre-dominants use #4 instead of 4. Chords applied to the dominant—V/V, V7/V, viio/V, viio7/V—are derived by chromatically altering ii or IV chords, but have a noticeably different effect than their diatonic forebears. Augmented sixths go one step further by adding further chromaticism with b6. Augmented-sixths as pre-dominants are similar to tonicizing applied chords (V/V, V7/V, viio/V, viio7/V) in that they contain #4, but differ from them in that they are not agents of tonicization. Augmented-sixths highlight the arrival of the dominant but do not tonicize it.