IV. Diatonic Harmony, Tonicization, and Modulation

John Peterson

Key Takeaways

This chapter introduces two strong predominants: IV and ii6.

• Both harmonize fa $(\hat{4})$ in the bass.
• They typically precede a dominant chord and predict that a dominant chord is on its way.
• The most common part-writing error when using strong predominants is parallel octaves or fifths.

As we noted in the Introduction to Harmony, Cadences, and Phrase Endings chapter, most phrase endings are strengthened using a strong that comes before the V chord (Example 1). Another way to say this is that it’s common for a phrase to end with the bass pattern fa–sol $(\hat4 - \hat5)$ in a or fa–sol–do $(\hat4 - \hat5 - \hat1)$ in an . The fa $(\hat{4})$ in the bass just before a cadence is the note that typically gets harmonized with a strong predominant (Example 2)—these chords are ii6 (the more common option) and IV.

Example 1. Strengthened ending with a strong PD in Maria Szymanowska, March no. 6 from Six Marches for Piano (0:00-0:16).

Example 2. Placement of strong predominant at a phrase ending.

# Writing with ii6

The strong predominant area adds a degree of challenge to writing because it’s where parallel octaves and fifths tend to show up (Example 3). You’ll want to carefully check your writing around strong predominants for parallels. One thing that can help is to make as many upper voices as possible in contrary motion with the bass. Since the bass will move up from fa to sol $(\hat{4}-\hat5)$, that means it’s best to move your upper voices down. Below are the steps for writing an authentic cadence. Note that if you want to write a half cadence, you just leave off the I chord at the end.

Example 3. Parallels in the strong predominant area.

### Steps for writing with ii6

1. Write the entire bass: fa–sol–do $(\hat4 - \hat5 - \hat1)$.
2. Write the entire soprano:
1. Start with the V chord, and place an in the soprano.
2. Resolve the active note appropriately over I.
3. Approach the active note from above to make contrary motion with the bass, or by .
3. Fill in the inner voices by asking “What do I have? What do I need? How should these voices move to create smooth motion and avoid parallels?”
1. In ii6, since it’s a first inversion chord, remember that you may double any note that gives you the smoothest voice leading and that avoids parallels.

This process is illustrated in Example 4.

Example 4. Writing with ii6.

# Writing with IV

The danger of writing parallels is even greater with IV than with ii6 because of the by step. Avoid doing something like Example 5, where all voices move upward in parallel motion. Just as with ii6, if you make your upper voices move in contrary motion to the bass (down) where possible, you’ll avoid the problem.

Example 5. Parallels created by moving all voices in the same direction.

The steps for writing with IV are the same as those for ii6: write the entire bass, write the entire soprano starting with V and working outward, then fill in the inner voices (Example 6). There’s one important difference with respect to doubling: whereas the ii6 chord’s doubling is quite flexible since it’s a first-inversion chord, the IV chord almost always sees its bass doubled since it’s a root-position chord.

Example 6. Writing with IV.

# Root position ii

The ii chord in root position is much less common than ii6 or IV, but it can be used as a strong predominant in major keys. (In minor keys, the iio chord, like any diminished triad, doesn’t normally show up in root position.)

While it’s possible to write parallels with ii, it’s less likely than with IV or ii6. Example 7 shows some common options. Note that it’s most common to place re or fa $(\hat2$ or $\hat4)$, not la $(\hat6)$, in the soprano over ii.

Example 7. Writing with ii.

# Using IV and ii(6) in combination

Sometimes a composer will choose to use both IV and ii(6) before the dominant at a phrase ending. In such cases, ii always comes after IV. Although both IV and ii(6) are strong pre-dominants, ii(6) shares a special relationship with the V chord that follows: the root of ii is a fifth away from the root of V, similar to how the root of V is a fifth away from the root of I (Example 8). This root relationship makes ii a stronger predominant than IV, which is why ii always comes after IV, never before IV, when both are used at a phrase ending.

Example 8. Comparison of root relationships between ii–V (left) and V–I (right).

Assignments
1. Strengthening Endings with Strong Predominants (.pdf, .docx). Includes part writing from Roman numerals and figures, analysis of phrase endings, and a discussion question about a number from Hamilton.