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IV. Diatonic Harmony, Tonicization, and Modulation
6/4 Chords as Forms of Prolongation

### Core Idea

This chapter introduces three additional ^6_4 chords beyond [cadential ^6_4](https://viva.pressbooks.pub/openmusictheory/chapter/endings-4-cadential-latexbeginsmallmatrix64endsmallmatrix-latex/). Passing (pass.) ^6_4 involves a passing tone in the bass that has been harmonized by a ^6_4 chord. It typically prolongs tonic or predominant harmonies, and it always occurs between two chords of the same function.

### Explanation

This chapter introduces three additional ^6_4 chords beyond cadential ^6_4.

Passing (pass.) ^6_4 involves a passing tone in the bass that has been harmonized by a ^6_4 chord. It typically prolongs tonic or predominant harmonies, and it always occurs between two chords of the same function.

Neighbor (n.) ^6_4 involves a static bass above which two of the upper voices perform upper neighbor motion. It typically prolongs tonic or dominant harmonies, and the chords on both sides of it are always in root position.

Arpeggiating (arp.) ^6_4 involves a bass that arpeggiates through the fifth of the chord while the upper voices sustain the chord in some way. It may prolong any harmony, and we don't typically bother recognizing it in analysis.

The table in Example 6 below summarizes the characteristics of each of the three types of ^6_4 that we advocate labeling in analysis.

Chapter Playlist

So far, we've seen that the tonic (T) area is most commonly prolonged using dominant-function chords, especially inverted \mathrm{V^7}s. In this chapter, we look at some additional, less common ways to prolong not only tonic chords, but also dominant and predominant chords. Earlier, we saw how ^6_4 chords are treated in special ways because they contain a dissonance with the bass (the fourth). We've already learned about \mathrm{cad.^6_4}; here, we turn to the three other ways ^6_4 chords can be used: passing ^6_4, neighboring ^6_4, and arpeggiating ^6_4. Note that in analysis, whenever you encounter a ^6_4 chord, you should stop and identify which kind it is (cadential, passing, neighboring, or arpeggiating) because the kind of ^6_4 determines the label. For ^6_4 chords, the Roman numeral by itself isn’t a sufficient label—the type also needs to be included.

Passing ^6_4

The passing (pass.) ^6_4 is a ^6_4 chord built on a passing tone in the bass (Example 1). It's most commonly found prolonging tonic or predominant harmonies. Importantly, the chords on both sides of the \mathrm{pass.^6_4} are always the same function (e.g., \mathrm{IV^6-pass.^6_4-ii^6}), not of different function (e.g., \mathrm{IV^6-pass.^6_4-I}).

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Example 1. \mathrm{pass.^6_4} in Beethoven, Piano Sonata Op. 14, no. 1, I, mm. 50–57 (1:28-1:42).

Example 2a demonstrates the steps for writing \mathrm{pass.^6_4} to expand tonic, and Examples 2b and 2c show several ways \mathrm{pass.^6_4} can prolong the predominant area. Note that each of these progressions can also work backward (e.g., \mathrm{I^6-pass.^6_4-I} also works).

To write with pass^6_4:

Write the entire bass. You should have three notes in stepwise motion where the first and last notes belong to the same functional area (T or PD). The middle note will be your passing tone.

Spell the pass.\mathbf{^6_4}. Just like with \mathrm{cad.^6_4}, to spell \mathrm{pass.^6_4}, determine what notes are a fourth and sixth above the bass. One voice will double the bass, just like in \mathrm{cad.^6_4}.

Write the entire soprano. The soprano should be a line that moves by step, not the static line.

Fill in inner voices, making them move as little as possible.

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Example 2. Writing with pass.\mathit{^6_4}.

Neighbor ^6_4

The neighbor (n.) ^6_4 consists of a static bass over top of which two voices have upper-neighbor motion (Example 3). Sometimes \mathrm{n.^6_4} is called pedal ^6_4, a name that reflects the static pedal in the bass. It's most commonly found prolonging I or V. Example 4a demonstrates the steps for writing \mathrm{n.^6_4} to prolong tonic, and Example 4b shows the voice leading to prolong V.

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Example 3. Neighbor and arpeggiating \mathit{^6_4} in Josephine Lang, "Dem Königs-Sohn."

To write with \mathrm{n.^6_4}:

Write the entire bass. The bass will be three of the same note, typically do–do–do or sol–sol–sol (\hat1-\hat1-\hat1 or \hat5-\hat5-\hat5)

Spell n.\mathbf{^6_4}. The \mathrm{n.^6_4} will be over the middle bass note. As with \mathrm{cad.} and \mathrm{pass.^6_4}, determine a sixth and fourth above the middle bass note. One voice will double the bass.

Write the entire soprano. For the soprano, choose either an upper-neighbor line or the static line. Unlike with \mathrm{cad.} or \mathrm{pass.^6_4}, \mathrm{n.^6_4} will more frequently have a static line in the soprano.

Fill in the inner voices, making them move as little as possible.

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Example 4. Writing with \mathit{n.^6_4}.

Arpeggiating ^6_4

Arpeggiating (arp.) ^6_4 is typically created when the bass leaps to the fifth of a chord while the upper voices sustain the chord. It's commonly found in, for example, ending bass arpeggiations (Example 3) or waltz-style accompaniments (Example 5). Unlike the other types, \mathrm{arp.^6_4} typically doesn’t need to be labeled in analysis. Example 5 identifies it using figures, but it’s not necessary to do so—each measure could simply be labeled as I.

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Example 5. Arpeggiating \mathit{^6_4} in Sophie de Auguste Weyrauch, Six Danses No. 3.

The table in Example 6 summarizes the characteristics of the three ^6_4 chord types that should be labeled in analysis. When you come across a ^6_4 chord in analysis, remember to stop and ask yourself what type it is (passing, neighboring, or cadential) and label it appropriately.

Example 6. Summary of \mathit{^6_4} chord types.

Assignments

^6_4 chords as forms of prolongation (.pdf, .docx). Asks students to review previous concepts, write from Roman numerals, write from figures, and analyze excerpts.

### Key Quote

It typically prolongs tonic or dominant harmonies, and the chords on both sides of it are always in root position.

### Application Scenarios

The table in Example 6 [below](#summary) summarizes the characteristics of each of the three types of ^6_4 that we advocate labeling in analysis.

The passing (pass.) ^6_4 is a ^6_4 chord built on a passing tone in the bass (Example 1). It's most commonly found prolonging tonic or predominant harmonies. Importantly, the chords on both sides of the \mathrm{pass.^6_4} are always the same function (e.g., \mathrm{IV^6-pass.^6_4-ii^6}), not of different function (e.g., \mathrm{IV^6-pass.^6_4-I}).

Example 1. \mathrm{pass.^6_4} in Beethoven, Piano Sonata Op. 14, no. 1, I, mm. 50–57 ([1:28-1:42](https://open.spotify.com/track/1TATwZjqU3I73RoGvWsVXA?si=c851bab266cd4f5b)).

[[B]]Example 2a[[/B]] demonstrates the steps for writing \mathrm{pass.^6_4} to expand tonic, and [[B]]Examples 2b [[/B]]and[[B]] 2c[[/B]] show several ways \mathrm{pass.^6_4} can prolong the predominant area. Note that each of these progressions can also work backward (e.g., \mathrm{I^6-pass.^6_4-I} also works).

### Key Terminology

root position prolongation neighboring dissonance cadential function harmony passing piano tonic chord root

### Related Links

cadential [latex]^6_4[/latex]Chapter Playlist[latex]\mathrm{cad.^6_4}[/latex]1:28-1:42 pdf docx
Source: https://viva.pressbooks.pub/openmusictheory/chapter/64-chords-as-prolongations/
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