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Figured bass
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Figured bass

A part notated with figured bass consists of a bass-line notated with notes on a musical staff plus added numbers and accidentals beneath the staff.  These indicate at which intervals above the bass line the additional notes should be played, ie which chords and inversions are to be played. The phrase tasto solo indicates that only the bass line (without any upper chords) is to be played for a short period, usually until the next figure is encountered.

Numbers

The numbers indicate the number of scale steps above the given bass-line that a note should be played. For example:

Here, the bass note is a C, and the numbers 4 and 6 indicate that notes a fourth and a sixth above it should be played, that is an F and an A. In other words, the second inversion of an F major chord is to be played.

A root position chord would be identified by 5 and 3, and a first inversion by 6 and 3.  However the numbers 3 or 5 are usually left out, owing to the frequency with which these intervals occur. For example:

In this sequence, the first note has no numbers accompanying it—both the 3 and the 5 have been omitted. This means that notes a third above and a fifth above should be played—in other words, a root position chord. The next note has a 6, indicating a note a sixth above it should be played; the 3 has been omitted—in other words, this chord is in first inversion. The third note has only a 7 accompanying it; here, as in the first note, both the 3 and the 5 have been omitted—the seven indicates the chord is a seventh chord. The whole sequence is equivalent to:

The performer must choose how to distribute or voice these notes: and also how to elaborate or decorate them with passing notes etc, in keeping with the style, tempo and texture of the work.

Sometimes, other numbers are omitted: a 2 on its own or 42 indicate 642, for example.  This produces a ii⁷d chord.

Sometimes the figured bass number changes but the bass note itself does not. In these cases the new figures are written wherever in the bar they are meant to occur. In the following example, the top line is a melody instrument:

When the bass note changes but the notes in the chord above it are to be held (eg. the bass line has a passing note), a line is drawn next to the figure or figures to indicate this:

The line extends for as long as the chord is to be held.

Accidentals

When an accidental is shown on its own without a number, it applies to the note a third above the lowest note; most commonly, this is the third of the chord. Otherwise, if a number is shown, the accidental affects the said interval. For example, this:

is equivalent to this:

Sometimes the accidental is placed after the number rather than before it.

Alternatively, a cross placed next to a number indicates that the pitch of that note should be raised by a semitone (so that if it is normally a flat it becomes a natural, and if it is normally a natural it becomes a sharp). A different way to indicate this is to draw a bar through the number itself. The following three notations, therefore, all indicate the same thing (but in ABRSM theory questions you will only see the first of them):

When sharps or flats are used with key signatures they may have a slightly different meaning, especially in 17th-century music. A sharp might be used to cancel a flat in the key signature, or vice versa, instead of a natural sign.

Example of Figured Bass in context. Taken from Beschränkt, ihr Weisen, by J.S. Bach (R. 47/69).

Bibliography

Butterworth, Anna (1999) Harmony in Practice, ABRSM.

Useful web sites

 http://www.design-bysarah.co.uk/oulinks/courses/a214/a214notes.htm  Notes from the Open University’s A214 course.

 http://www.musictheoryminute.com Theory resource with keyboard demonstrations on video.

 http://www.dolmetsch.com/theoryindex.htm This is the index page to Dr Brian Blood's invaluable theory and harmony resource.