IV. Diatonic Harmony, Tonicization, and Modulation
IV. Diatonic Harmony, Tonicization, and Modulation
La (6̂) in the Bass at Beginnings, Middles, and Endings
John Peterson
Key Takeaways
This chapter discusses the various ways in which composers harmonize la [latex](\hat6)[/latex] in the bass depending on where it’s found within a phrase: beginning, middle, or ending.
- At phrase beginnings, la [latex](\hat6)[/latex] is often used to prolong tonic in two ways:
- harmonized with IV6 in the progression [latex]\mathrm{I-IV^6-V^6_5-I}[/latex] ( and )
- harmonized with plagal (IV6) in the progression [latex]\mathrm{I-IV^6-I^6}[/latex] ( and )
- At phrase middles, la [latex](\hat6)[/latex] is often used:
- in a deceptive motion (V(7)–vi) ( and )
- to connect the tonic (T) and strong predominant (PD) areas, harmonized with vi ( and )
- At phrase endings, la [latex](\hat6)[/latex] is often used:
- to create a phrygian half cadence (iv6–V in minor) ( and )
- as a “stand-in” for the expected strong PD note fa [latex](\hat4)[/latex] ( )
Overview: uses of la (scale degree 6)
So far, we’ve seen every scale degree appear in the bass except for la [latex](\hat6)[/latex]. In this chapter, we see that la [latex](\hat6)[/latex] is commonly harmonized by two chords: vi or IV6. It may show up in beginnings, middles, or endings of phrases, and each location is associated with particular progressions that involve la [latex](\hat6)[/latex] in the bass.
At phrase beginnings
When la [latex](\hat6)[/latex] appears in the bass at the beginning of a phrase, it typically prolongs tonic in one of two ways: (1) using IV6 as a predominant in the progression [latex]\mathrm{I-IV^6-V^6_5-I}[/latex] (
), or (2) using plagal (IV6) in the progression [latex]\mathrm{I-IV^6-I^6}[/latex] ( ).
Using IV6 as a predominant
Writing [latex]\mathrm{I-IV^6-V^6_5-I}[/latex] can be tricky, particularly when [latex]\mathrm{IV^6}[/latex] goes to [latex]\mathrm{V^6}[/latex], since there is a danger both of parallels and of a doubled leading tone. No single piece of advice can guarantee that you’ll avoid problems. When you write [latex]\mathrm{I-IV^6-V^6_5-I}[/latex], the soprano lines do–do–re–do [latex](\hat1-\hat1-\hat2-\hat1)[/latex] and mi–mi–fa–mi [latex](\hat3-\hat3-\hat4-\hat3)[/latex] will help, but you’ll need to check carefully for parallels. Using [latex]\mathrm{V^6_5}[/latex] instead of [latex]\mathrm{V^6}[/latex] will also mitigate some of the danger of parallels (
). Note that this progression doesn’t work well in minor, where the bass would create an augmented second from le to ti [latex](\downarrow\hat6-\uparrow\hat7)[/latex]. The rare occurrences of this progression in minor raise le to la [latex](\downarrow\hat6[/latex] to [latex]\uparrow\hat6)[/latex] to avoid the augmented second ( and ).
Using plagal (IV6)
Writing [latex]\mathrm{I-IV^6-I^6}[/latex] is relatively easy (
). Here, remember three things:- The bass always arpeggiates down.
- The most common soprano is mi–fa–sol [latex](\hat3-\hat4-\hat5)[/latex].
- The other voices sh