IV. Diatonic Harmony, Tonicization, and Modulation

# Prolonging Tonic at Phrase Beginnings with V6 and Inverted V7s

John Peterson

Key Takeaways

- Prolongation is a common feature of phrase beginnings in Western classical music.
- The most common way to prolong the tonic is by alternating tonic with V
^{6}or inverted V^{7}chords.

# Overview

Phrase beginnings in Western classical music typically feature a prolongation of tonic harmony to establish the home key. “Prolongation” just means that the harmony’s influence lasts longer than a single chord. Say, for example, that you bought a serving of ice cream that you wanted to enjoy over an extended period. One way to do it would be to take small bites to extend the length of time you’re eating. While this method would work, you might be eating ice cream soup by the end. Another way to do it would be to eat some, put it in the freezer, do some other activity, then come back and eat some more. You might say, “I’ve been eating ice cream all day,” even though you haven’t literally been eating ice cream every second of the day (as much as you might want to).

Something analogous happens in music. We could prolong the tonic’s importance at the beginning of a phrase by holding or repeating the chord (like taking small bites of the ice cream), as in

, but more interesting and rewarding is to use other chords between instances of the tonic (like putting the ice cream in the freezer and coming back to it later).

^{7}s between tonic triads. The tonic’s influence is felt more strongly because (1) it’s on stronger beats or hyperbeats than the V^{7}, and (2) it appears at least once in root position, whereas the V^{7} is in a weaker inversion.

# Writing Tonic Prolongations

The tonic prolongations covered in this chapter are the ones most commonly seen in Western classical music, and they all share several traits:

- They are three chords long
- The first and last chords are I or I
^{6} - The middle chord is V
^{6}or an inverted V^{7} - The V
^{6}or inverted V^{7}resolves using the same principles we learned in Strengthening Endings with Cadential [latex]^6_4[/latex]

## Prolonging with V6/5 and V6

[latex]\mathrm{V}^6_5[/latex] typically prolongs root position I in the progression [latex]\mathrm{I-V^6_5-I}[/latex] (*ti* ([latex]\hat{7}[/latex]) is in the bass, and we know that *ti* ([latex]\hat{7}[/latex]) must resolve to *do* ([latex]\hat{1}[/latex]). As always, follow the typical writing procedure.

It’s also possible to prolong tonic with V^{6} rather than [latex]\mathrm{V}^6_5[/latex], though this is less common ( ).

## Prolonging with V4/2

[latex]\mathrm{V}^4_2[/latex] usually helps us move from root position to first inversion I in the progression [latex]\mathrm{I-V^4_2-I^6}[/latex] (*fa* ([latex]\hat{4}[/latex]) in the bass, which must resolve to *mi* ([latex]\hat{3}[/latex]) since *fa* ([latex]\hat{4}[/latex]) is the chordal seventh. Again, follow the typical writing procedure.

## Prolonging with V4/3

Most commonly, [latex]\mathrm{V}^4_3[/latex] helps us move from root position to first inversion I in the progression [latex]\mathrm{I-V^4_3-I^6}[/latex] (*re* ([latex]\hat{2}[/latex]), may go either to *do* ([latex]\hat{1}[/latex]) or to *mi* ([latex]\hat{3}[/latex]). Again, follow the typical writing procedure.

Writing with [latex]\mathrm{V}^4_3[/latex] also offers one exception to the rule that the chordal seventh, *fa* ([latex]\hat{4}[/latex]), must resolve down ( ). Here, *fa *moves up to *sol* ([latex]\hat4-\hat5[/latex]). This exception is made possible because the bass creates parallel tenths with the upper voice that takes the line *mi*–*fa*–*sol* ([latex]\hat3-\hat4-\hat5[/latex]).

# Combining Progressions

By chaining together several of these tonic prolongation progressions, composers can extend the tonic’s influence for quite a while at the beginning of a phrase, as in

A part-written example is given in

# Bass Line Summary

A summary of the four tonic-prolongation bass lines discussed in this chapter, along with their associated progressions, is given in

Bass | Progression |
---|---|

do–ti–do ([latex]\hat{1}[/latex]–[latex]\hat{7}[/latex]–[latex]\hat{1}[/latex]) |
[latex]\mathrm{I}[/latex]–[latex]\mathrm{V}\begin{smallmatrix}6\\(5)\end{smallmatrix}[/latex]–[latex]\mathrm{I}[/latex] |

do–re–mi ([latex]\hat{1}[/latex]–[latex]\hat{2}[/latex]–[latex]\hat{3}[/latex]) |
[latex]\mathrm{I}[/latex]–[latex]\mathrm{V}\begin{smallmatrix}4\\3\end{smallmatrix}[/latex]–[latex]\mathrm{I}^{6}[/latex] |

do–re–do ([latex]\hat{1}[/latex]–[latex]\hat{2}[/latex]–[latex]\hat{1}[/latex]) |
[latex]\mathrm{I}[/latex]–[latex]\mathrm{V}\begin{smallmatrix}4\\3\end{smallmatrix}[/latex]–[latex]\mathrm{I}[/latex] |

do–fa–mi ([latex]\hat{1}[/latex]–[latex]\hat{4}[/latex]–[latex]\hat{3}[/latex]) |
[latex]\mathrm{I}[/latex]–[latex]\mathrm{V}\begin{smallmatrix}4\\2\end{smallmatrix}[/latex]–[latex]\mathrm{I}^{6}[/latex] |

- Prolonging Tonic at Phrase Beginnings with V
^{6}and Inverted V^{7}(.pdf, .docx, recording). Asks students to write from Roman numerals and figures and complete a guided analysis. Download score.

When a given harmony’s influence lasts longer than a single chord. Usually this is accomplished by alternating the prolonged chord with other, less important chords.

1. Write the entire bass

2. Write the entire soprano to make a smooth melody that interacts well with the bass. Choose active notes for the soprano above dominant-function chords, and remember you do not always need to write left to right.

3. Write the inner voices by asking, "What notes do I already have? What notes do I still need? Considering spacing and resolution, what note placement would give me the smoothest motion?"