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Figured bass, or thoroughbass, is a kind of musical notation in which numerals and symbols (often accidentals) indicate intervals, chords, and non-chord tones that a musician playing harpsichord, organ, lute (or other instruments capable of playing chords) play in relation to the bass note that these numbers and symbols appear above or below. Figured bass is closely associated with basso continuo, a historically improvised accompaniment used in almost all genres of music in the Baroque period of Classical music (ca. 1600-1750), though rarely in modern music. Other systems for denoting or representing chords include〔.〕 plain staff notation, used in classical music; Roman numerals, commonly used in harmonic analysis;〔.〕 macro symbols, sometimes used in modern musicology; the Nashville number system; and various names and symbols used in jazz and popular music. ==Basso continuo== Basso continuo parts, almost universal in the Baroque era (1600–1750), provided the harmonic structure of the music. The phrase is often shortened to ''continuo'', and the instrumentalists playing the continuo part, if more than one, are called the ''continuo group''. The titles of many Baroque works make mention of the continuo section, such as J. S. Bach's Concerto for Two Violins, Strings and Continuo in D Minor. The makeup of the continuo group is often left to the discretion of the performers, and practice varied enormously within the Baroque period. At least one instrument capable of playing chords must be included, such as a harpsichord, organ, lute, theorbo, guitar, regal, or harp. In addition, any number of instruments which play in the bass register may be included, such as cello, double bass, bass viol, or bassoon. The most common combination, at least in modern performances, is harpsichord and cello for instrumental works and secular vocal works, such as operas, and organ for sacred music. Typically performers match the instrument families used in the full ensemble: including bassoon when the work includes oboes or other winds, but restricting it to cello and/or double bass if only strings are involved. Harps, lutes, and other handheld instruments are more typical of early 17th-century music. Sometimes instruments are specified by the composer: in ''L'Orfeo'' (1607) Monteverdi calls for an exceptionally varied instrumentation, with multiple harpsichords and lutes with a bass violin in the pastoral scenes followed by lamenting to the accompaniment of ''organo di legno'' and ''chitarrone'', while Charon stands watch to the sound of a regal. The keyboard (or other chording instrument) player ''realizes'' a continuo part by playing, in addition to the indicated bass notes, upper notes to complete chords, either determined ahead of time or improvised in performance. The figured bass notation, described below, is a guide, but performers are also expected to use their musical judgment and the other instruments or voices (notably the lead melody) as a guide, and experienced players often incorporate motives found in the other instrumental parts. Modern editions of such music usually supply a realized keyboard part, fully written out for a player, in place of improvisation. With the rise in historically informed performance, however, the number of performers who are able to improvise their parts from the figures, as Baroque players would have done, has increased. Basso continuo, though an essential structural and identifying element of the Baroque period, continued to be used in many works, especially sacred choral works, of the classical period (up to around 1800). An example is C. P. E. Bach's Concerto in D minor for flute, strings and basso continuo. Examples of its use in the 19th century are rarer, but they do exist: masses by Anton Bruckner, Beethoven, and Franz Schubert, for example, have a basso continuo part for an organist to play. ==Figured bass notation== 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 to indicate what intervals above the bass notes should be played, and therefore which inversions of which chords 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. Composers were inconsistent in the usages described below. Especially in the 17th century, the numbers were omitted whenever the composer thought the chord was obvious. Early composers such as Claudio Monteverdi often specified the octave by the use of compound intervals such as 10, 11, and 15. Contemporary figured bass may be summarized as follows: For diatonic triads: *root position = blank or *1st Inversion = 6 or *2nd Inversion = For 7th chords: *root position = 7 *1st Inversion = *2nd Inversion = *3rd Inversion = 2 or 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Figured bass」の詳細全文を読む スポンサード リンク
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