Strengthening Endings with Cadential 6/4

John Peterson

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So far, we’ve seen that the dominant can be strengthened, particularly at authentic cadences, by the addition of a 7^th. We also saw that both half cadences and authentic cadences are commonly strengthened using a strong predominant. In this chapter, we look at another way to strengthen the dominant’s desire for resolution: [latex]\mathrm{cadential}^6_4[/latex] [latex](\mathrm{cad.}^6_4).[/latex]

The authentic cadence in Example 1 involves a V⁷ that has been embellished by [latex]\mathrm{cad.}^6_4[/latex]. We use the word “embellished” intentionally here because the [latex]\mathrm{cad.}^6_4[/latex] is comprised of two embellishing tones that appear over Sol ([latex]\hat{5}[/latex]) in the bass. In Example 1, the embellishing tones are a passing tone and a suspension. These embellishing tones happen to always be a 6^th and a 4^th above the bass, and their appearance often intensifies our desire for a cadence, hence the name “[latex]\mathrm{cad.}^6_4[/latex].” Although the [latex]\mathrm{cad.}^6_4[/latex] often shows up at cadence points, it may show up anywhere in a phrase as an embellishment of V⁽⁷⁾.

Example 1. [latex]cad.\mathit{^6_4}[/latex] in Joseph Boulogne’s String Quartet 4, I, mm. 45–47 (1:26–1:30).

Labeling cadential 6/4

You might have noticed that the [latex]\mathrm{cad.}^6_4[/latex] in Example 1 involves the notes B [latex]\flat[/latex], G, and E [latex]\flat[/latex], which spells a tonic triad in second inversion in the excerpt’s key. Why are we labeling this chord [latex]\mathrm{V}^6_4[/latex] then? Besides the fact that [latex]\mathrm{cad.}^6_4[/latex] arises from the combination of two embellishing tones (and therefore it isn’t a standalone triad), here are two additional reasons we favor the label [latex]\mathrm{V}^6_4[/latex] over I[latex]^6_4[/latex]:

1. The chord appears after a strong predominant. If we label it [latex]\mathrm{I}^6_4[/latex], we’d be implying a predominant goes to tonic, which is not the sound we hear given that Sol ([latex]\hat{5}[/latex]) is in the bass.
2. [latex]\mathrm{V}^6_4[/latex] reflects the chord’s sound as an elaboration of V, whereas I[latex]^6_4[/latex] reflects the chord’s spelling only. Since music is an auditory art, we prefer the label that expresses how the chord sounds.^[1]

Writing with cadential 6/4

Spelling cadential 6/4 in four voices

To spell [latex]\mathrm{cad.}^6_4[/latex], do the following (Example 2):

1. Write sol ([latex]\hat{5}[/latex]) in the bass
2. Determine what notes are a 6^th and 4^th above the bass. Choose one of those notes to place in the soprano. The other will go in an inner voice in step 3.
3. Fill in the inner voices: one voice will double the bass, which is a necessity in [latex]\mathrm{cad.}^6_4[/latex] to avoid parallels. The other will take the unused note from step 2.

Example 2. Spelling [latex]cad.\mathit{^6_4}[/latex].

Voice leading with cadential 6/4

Resolution

Cadential [latex]^6_4[/latex] can resolve either to a V triad (Examples 3a, 3c) or a V⁷ chord (Examples 3b, 3d). The lines in the label [latex]\begin{smallmatrix}6-5\\4-3\end{smallmatrix}[/latex] tell you how the [latex]\mathrm{cad.}^6_4[/latex] resolves. Those lines mean “keep this motion in the same voice.” That is, whichever voice has a 6^th above the bass should fall to a 5^th above the bass, and whichever voice has the 4^th above the bass should fall to a 3^rd above the bass.

Adding a 7^th is easy, too! Whatever voice is doubling the bass moves down a step to take the 7^th of the chord. This motion is reflected by the figures 8-7 (the octave above the bass moves down to a 7^th above the bass).

Example 3. Resolving [latex]cad.\mathit{^6_4}[/latex].

Approaching cadential 6/4

Since the [latex]\mathrm{cad.}^6_4[/latex] embellishes the dominant, any harmony that approaches V can also approach [latex]\mathrm{cad.}^6_4[/latex]. Most commonly, though, these are the strong predominants IV and ii⁶ (Example 4).

Two guidelines apply here:

1. As always when dealing with the predominant area, watch out for parallel octaves between the predominant and [latex]\mathrm{cad.}^6_4[/latex].
2. Motion into (and out of) the [latex]\mathrm{cad.}^6_4[/latex] is usually very smooth. Avoid leaping to a member of the [latex]\mathrm{cad.}^6_4[/latex]. While composers do occasionally leap to the 6^th above the bass, it’s comparatively much rarer to leap to the 4^th above the bass because it’s a dissonance. So especially avoid that.

Example 4. Approaching [latex]cad.\mathit{^6_4}[/latex].

1. Strengthening Endings with Cadential [latex]^6_4[/latex] (.pdf, .docx, .mscz of score). Includes unfigured bass exercises and analysis.