Figured Bass Realization

Introduction: The Baroque Shorthand

In the Baroque era (about 1600–1750), composers rarely wrote out every note of the accompaniment. Instead they gave the keyboard or lute player a bass line with small numbers under it, a figured bass, and trusted the player to fill in the harmony on the spot. That improvised part is called the continuo (or basso continuo), and the act of filling it in is called realizing the figured bass.

Figured bass is the ancestor of the Roman numerals and inversion symbols you already know. Learning to read it gives you a direct line into how Bach, Handel, and Corelli thought about harmony, and it's still the fastest way to sketch four-part writing.

Click any example to hear it.

The Basic Rule: Intervals Above the Bass

Each figure is an interval above the bass note, counted by letter name and spelled using the key signature. Figures don't tell you which octave or which voice gets each note; they only tell you which pitch classes to include.

• A 6 under a bass note D (in C major) means: include the note a 6th above D (B) and, by assumption, the 3rd above (F). The chord is D–F–B: vii°⁶.
• Compound intervals are reduced: a 10th is shown as a 3.
• When a figure is missing, assume the most common chord: a root-position triad (5/3).

The Standard Figures

Full figures list every interval above the bass, but players used abbreviations. These are the ones you need to memorize:

Notice that the abbreviations are exactly the inversion symbols you've been writing next to Roman numerals since Chapter 7. That's where they came from.

Accidentals in the Figures

Because figures are spelled from the key signature, any note that isn't in the key needs an accidental in the figure:

• An accidental alone (♯, ♭, or ♮) applies to the third above the bass. In minor keys you'll see a lone ♯ (or ♮) under 5̂ all the time: it raises the third of V to make the leading tone.
• An accidental next to a number applies to that interval: ♯6 means "raise the sixth above the bass."
• A slash through a number (6̸) or a plus sign (4+) also means "raise this note."
• The accidental changes the upper note. The bass note's own accidentals are written on the staff, as usual.

Realizing a Figured Bass, Step by Step

1. Read the key from the key signature and the final bass note.
2. Spell each chord: for every bass note, find the intervals above it that the figure asks for (fill in any assumed ones), and apply any accidentals.
3. Name the chord with a Roman numeral. This tells you its function and which notes are tendency tones.
4. Plan the soprano: a mostly stepwise line, moving contrary to the bass when you can.
5. Fill in the alto and tenor using everything from Volume I: keep common tones, move by step, resolve the leading tone and chordal sevenths, avoid parallel fifths and octaves, and follow the doubling rules (never double the leading tone; in a 6/4, double the bass).

Moving Figures and Suspensions

Sometimes two figures appear one after the other under a single bass note, like 4–3 or 6–5. These mean an upper voice moves while the bass holds: a 4th above the bass falling to a 3rd is exactly the 4–3 suspension from Chapter 12. The common cadential pattern 6/4–5/3 over 5̂ is the cadential six-four. A horizontal line after a figure means "keep holding these notes."

Try It: The Figure Decoder

Summary

• Figures are intervals above the bass, spelled with the key signature; abbreviations stand for full figures (6 = 6/3, 4/3 = 6/4/3).
• A lone accidental alters the third above the bass; an accidental beside a number alters that interval; a slash or + raises.
• Realize by spelling each chord, naming its function, planning the soprano, and then voicing with all the part-writing rules.
• The figures fix the harmony, not the voicing: many different realizations can be correct.

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