Figured bass is a coded, shorthand method of musical notation for the lower bass section of a musical composition. It relies on the musician’s technical knowledge of how the intervals, or distances, between pitches create harmonic chords. The progression of chords, defined as the combined sound of two or more musical notes, is one of the most important structural backbones of music. The absence of detailed notation in figured bass also relies on the musician’s ability to improvise support for melody and the upper treble sections of a composition.
The notation technique was in common use during music’s Baroque period from 1600 to 1760 which featured composers like Johann Sebastian Bach who were especially fond of music for virtuoso solo instruments. It was termed “basso continuo,” which translates to continuous bass in Italian. Another term for figured bass in English is “thoroughbass.” The continuo of a Baroque composition usually consisted of a group of indeterminate instruments to play back-up bass music to featured soloists. This archaic system of notation is rarely seen in modern sheet music, but remnants of it are evident in the names of stringed guitar chords and in the notations of academic music theory.
The musical scale consists of seven, repeating intervals — C-D-E-F-G-A-B — plus half-tones between them represented by the familiar pattern of black keys on a piano. A major chord in root position consists of any note, designated the first interval, combined with its third and fifth intervals. Counting the letters as numbers, a C-major chord is therefore C+E+G. The scale repeats, allowing the same chord to be played as E+G+C — a first, plus its third and sixth intervals. This is referred as a C-major chord in its 1st inversion position.
The shorthand code of figured bass in sheet music uses these numeric values for intervals. The traditional bass staff of five lines and four spaces is written as a simple sequence of single notes, but they are annotated by numbers to designate compatible intervals. A note accompanied by the number 6 defines 1st inversion. The notation 6/4 indicates 2nd inversion position — a note, plus its fourth and sixth interval, or G+C+E in the case of C-major. Annotation of accidental marks — sharps, flats and naturals — indicates half-tone adjustments to an interval, resulting in minor or augmented chords, such as the C+E-flat+G for C-minor.
A bass section has the unique purpose of accompaniment to most pieces of music. It provides choral harmony to melodies. They are walking, striding, marching or punctuated rhythms. It is entirely variable and dependent on effect, or the tone and style of music to be achieved. Rather than a difficult note-by-note transcription of sheet music, many musicians appreciate shorthand notation of chord structures and progression to play for its intended effect by feel.
Musicians of instruments with the ability to play a chord in different fingered patterns also appreciate the basic technique of notation with figured bass. As in the case of a piano, for example, numeric translation often comes naturally from early learning — thumb, first finger, second, and so forth. Guitar chords bear numeric, and accidental, assignments to their names to indicate inversion positions, and additional or subtractive intervals. Traditional notation for academics of music theory employ a combination of roman numerals and integers to analyze chord progressions.