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II. Counterpoint and Galant Schemas
Ground Bass

### Core Idea

Ground bass compositions have a bass line that repeats continually throughout. This chapter focussed on the use of grounds in baroque context (like trio sonatas) where variety is created through textural and harmonic change in parts above the bass line, notably with:

### Explanation

Ground bass compositions have a bass line that repeats continually throughout.

This chapter focussed on the use of grounds in baroque context (like trio sonatas) where variety is created through textural and harmonic change in parts above the bass line, notably with:

re-harmonisation of the bass, often to suggest local tonicizations of other keys;

lively imitation and interplay between the upper parts.

Ground bass compositions are based on a bass line that repeats throughout the piece, usually exactly, or nearly so. Many musicians have found this a compelling compositional constraint for keeping themselves ... well ... grounded!

How many musicians are we talking about? Well, this practice was highly popular in the Baroque (Purcell was a particularly keen and expert protagonist), it is even more common in popular songs of recent years (see Harmonic Schemas in Pop Music), and there are more than a few examples from in between. In short, it is an extremely and enduringly popular form.

It's easy to confuse "ground bass" with some other terms; going from broad to specific, the key terms to distinguish are:

Ostinato: any pattern that repeats throughout a long section or whole work in one voice, like the motto side drum rhythm of Ravel’s Boléro.

Ground bass: a specific type of ostinato in which a bass line repeats throughout a work or section. The work itself can also be called a ground bass.

Chaconne and Passacaglia (and international variant spellings such as "Chacony"): sub-genres of the Baroque ground bass. Among their other characteristics, both of these two are in triple meter. Every Chaconne or Passacaglia is also a ground bass, and every ground bass is also an ostinato, but the reverse is not true: not every ostinato is a ground bass, and not every ground bass is a Chaconne or Passacaglia.

This chapter provides some files and instructions to help you explore some of the ways to create effective ground bass compositions. We focus on the Baroque model, and on creating variety through re-harmonizing the same bass in different ways and varying the texture.

Multiple Harmonizations of a Given Bass

Continually using the same repeating bass line throughout could get tedious, and is especially liable to make the harmony extremely static. To that effect, inventive composers find ways to re-harmonize the same bass line to move to other keys, or at least hint at such a move. This often relies on seeing the different ways in which a single interval in the bass could be reinterpreted.

While this might not seem like much to work with, this bass harmonization "cheat sheet" (PDF) shows that there are many ways to re-harmonize bass intervals. It is organized by bass interval: both ascending and descending forms of each interval from minor seconds to tritones. Note that this is supposed to help you work out your options—you definitely don't need to use all of these! We'll see below how Purcell uses just a few of these to create harmonic variety in a very long work that's almost entirely in G minor. We'll be especially interested in moments where Purcell avoids the main perfect cadence at the start/end of each iteration of the ground, joining two grounds together with a subtler seam and thereby varying not only the harmony but also the phrase rhythm of the piece.

Analysis: Purcell's Sonata in G Minor (Z 807)

To explore some of the options here, let's take a look at Purcell's Sonata in G Minor (Z 807). We'll look at how Purcell uses (extensive) imitation and (occasional) tonicization. All of these matters are also included on the score as text annotations at the relevant moment (Example 1).

Harmony

Harmonically, the piece is resolutely in G minor almost throughout, though Purcell tonicizes several keys along the way. The full list of tonicizations is (arguably):

Dmi in measure 17

F in measure 27

B♭ in measure 28

Cmi in measure 33

E♭ in measure 78

F in measure 87

E♭ in measure 88

Cmi in measure 93

Dmi in measure 107

F in measure 117

Cmi in measure 131 (beat 3) and in measure 133

E♭ in measure 158

E♭ in measure 163

Notice especially how Purcell finesses that boundary between the start and end of a ground iteration by avoiding yet another perfect cadence in G minor. For instance, see m. 16 and m. 106 for uses of G major as part of V^4_2/v–v6, broadly reversing tonic and dominant function, and likewise m. 26 and m. 86 for G diminished as viio6–I in F major. These special cases are marked on the score.

As a wider matter, notice how extensively Purcell uses 5–6 steps in the melodic parts and how this creates ambiguity in the harmony, as in m. 1 and m. 12. Is the 5 or the 6 harmonic, or perhaps both? Is this consistent, or does it change? This all makes it harder to pin down exactly what the harmony is and where it changes, adding ever further layers of interest to the score. It also helps set up the sequences of 7–6 suspensions such as from m. 71.

Imitation

Imitation is prevalent throughout. The melodic imitations are labeled "D" and "C" on the score. This is short for dux (leader) and comes (follower). For instance, the violin 1 parts starts a melodic line in measure 1 (beat 1), which is imitated by the violin 2 entering in measure 3 (beat 1).

Notice how often these imitations start in the same part of the bar. This is consistent with what we discussed in the context of 16th-century and 18th-century imitative traditions. Entering on equivalent beats leads to temporal gaps between entries of three or six beats (beat gaps on the table). Then again, note how Purcell occasionally uses closer imitation in measures 36, 41, 56, 63, 71, 133, 171, 178, 181, and 182.

As the score shows, there is

### Key Quote

Ground bass compositions are based on a bass line that repeats throughout the piece, usually exactly, or nearly so.

### Application Scenarios

How many musicians are we talking about? Well, this practice was highly popular in the Baroque (Purcell was a particularly keen and expert protagonist), it is even more common in popular songs of recent years (see [Harmonic Schemas in Pop Music](https://viva.pressbooks.pub/openmusictheory/chapter/pop-rock-schemata/)), and there are more than a few examples from in between. In short, it is an extremely and enduringly popular form.

To explore some of the options here, let's take a look at Purcell's Sonata in G Minor (Z 807). We'll look at how Purcell uses (extensive) imitation and (occasional) tonicization. All of these matters are also included on the score as text annotations at the relevant moment (Example 1).

[[B]]Annotate scores:[[/B]] Baroque ground bass compositions with analytical annotations including an attempt at full Roman numeral analysis, despite the contrapuntal nature of many of these works. The Purcell above is an example of this.

Purcell Sonata in G Minor Z807 (the example on this page)

### Key Terminology

triple meter ground bass bass line imitation interval ostinato harmony section texture rhythm meter form

### Related Links

Harmonic Schemas in Pop Music this bass harmonization "cheat sheet" (PDF)16th-century 18th-century the above Purcell score hosted on OMTs MuseScore page a more thoroughly annotated version of this Purcell score on FourScoreAndMore's MuseScore page Four Score and More wider set of templates and annotations files on Four Score and More's MuseScore.com page
Source: https://viva.pressbooks.pub/openmusictheory/chapter/ground-bass/
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