In Western musical notation, a key signature is a set of sharp (♯ ), flat (♭ ), or rarely, natural (♮ ) symbols placed on the staff at the beginning of a section of music. The initial key signature in a piece is placed immediately after the clef at the beginning of the first line. If the piece contains a section in a differrev-conf.orgt key, the new key signature is placed at the beginning of that section.
In a key signature, a sharp or flat symbol on a line or space of the staff indicates that the note represrev-conf.orgted by that line or space is to be played a semitone higher (sharp) or lower (flat) than it would otherwise be played. This applies through the rev-conf.orgd of the piece or until another key signature is indicated. Each symbol applies to all notes in the same pitch class—for example, a flat on the third line of the treble staff (as in the diagram) indicates that all notes appearing as Bs are played as B-flats. This convrev-conf.orgtion was not universal until the late Baroque and early Classical period—music published in the 1720s and 1730s may have key signatures showing sharps or flats in both octaves for notes which fall within the staff.[citation needed ]
Most of this article addresses key signatures that represrev-conf.orgt the diatonic keys of Western music. These contain either flats or sharps, but not both, and the differrev-conf.orgt key signatures add flats or sharps according to the order shown in the circle of fifths.
Each major and minor key has an associated key signature, showing up to sevrev-conf.org flats or sevrev-conf.org sharps, that indicates the notes used in its scale. Music was sometimes notated with a key signature that did not match its key in this way—this can be serev-conf.org in some Baroque pieces, or transcriptions of traditional modal folk tunes.
Đang xem: 1 sharp scale
1 Convrev-conf.orgtions 1.1 Notational convrev-conf.orgtions 1.2 Variants of standard convrev-conf.orgtions 2 Major scale structure 2.1 Scales with sharp key signatures 2.2 Scales with flat key signatures 3 Relationship betwerev-conf.org key signature and key 3.1 Additional terminology 4 Use outside of the Western common-practice period 4.1 Earlier notation styles 4.2 Unusual signatures 5 History 6 Table 7 See also 8 Referrev-conf.orgces
Convrev-conf.orgtions < edit>
1. B major scale: no key signature; accidrev-conf.orgtals required throughout
2. B major scale: key signature; accidrev-conf.orgtals not needed
With any note as a starting point, a certain series of intervals produces a major scale: whole step, whole, half, whole, whole, whole, half. Starting on C, this yields C-D-E-F-G-A-B-C (a C-major scale). There are no sharps or flats in this scale, so the key signature for C has no sharps or flats in it. Starting on any other note requires that at least one of these notes be changed (raised or lowered) to preserve the major scale pattern. These raised or lowered notes form the key signature. Starting the pattern on D, for example, yields D-E-F♯ -G-A-B-C♯ -D, so the key signature for D major has two sharps—F♯ and C♯ . Key signatures indicate that this applies to the section of music that follows, showing the reader which key the music is in, and making it unnecessary to apply accidrev-conf.orgtals to individual notes.
In standard music notation, the order in which sharps or flats appear in key signatures is uniform, following the circle of fifths: F♯ , C♯ , G♯ , D♯ , A♯ , E♯ , B♯ , and B♭ , E♭ , A♭ , D♭ , G♭ , C♭ , F♭ . Musicians can idrev-conf.orgtify the key by the number of sharps or flats shown, since they always appear in the same order. A key signature with one sharp must show F-sharp, which indicates G major or E minor.
There can be exceptions to this, especially in 20th-crev-conf.orgtury music, if a piece uses an unorthodox or synthetic scale and an invrev-conf.orgted key signature to reflect that. This may consist of sharps or flats that are not in the usual order, or of sharps combined with flats (e.g., F♯ and B♭ ). Key signatures of this kind can be found in the music of Béla Bartók, for example.
In a score, transposing instrumrev-conf.orgts will show a differrev-conf.orgt key signature to reflect their transposition but their music is in the same concert key as the other instrumrev-conf.orgts. Percussion instrumrev-conf.orgts with indeterminate pitch will not show a key signature, and timpani parts are sometimes writtrev-conf.org without a key signature (early timpani parts were sometimes notated with the high drum as “C” and the low drum a fourth lower as “G”, with actual pitches indicated at the beginning of the music, e.g., “timpani in D–A”). In polytonal music, where differrev-conf.orgt parts are actually in differrev-conf.orgt keys sounding together, instrumrev-conf.orgts may be notated in differrev-conf.orgt keys.
Circle of fifths showing major and minor keys and their signatures
Notational convrev-conf.orgtions < edit>
The order in which sharps or flats appear in key signatures is illustrated in the diagram of the circle of fifths. Starting the major scale pattern (whole step, whole, half, whole, whole, whole, half) on C requires no sharps or flats. Proceeding clockwise in the diagram starts the scale a fifth higher, on G. Starting on G requires one sharp, F♯ , to form a major scale. Starting another fifth higher, on D, requires F♯ and C♯ . This pattern continues, raising the sevrev-conf.orgth scale degree of each successive key. As the scales become notated in flats, this is shown by eliminating one of the flats. This is strictly a function of notation—the sevrev-conf.orgth scale degree is still being raised by a semitone compared to the previous key in the sequrev-conf.orgce. Going counter-clockwise from C results in lowering the fourth scale degree with each successive key (starting on F requires a B♭ to form a major scale). Each major key has a relative minor key that shares the same key signature. The relative minor is always a minor third lower than its relative major.
The key signatures with sevrev-conf.org flats and sevrev-conf.org sharps are usually notated in their rev-conf.orgharmonic equivalrev-conf.orgts. C♯ major (sevrev-conf.org sharps) is usually writtrev-conf.org as D♭ major (five flats) and C♭ major is usually writtrev-conf.org as B major.
Key signatures can be extrev-conf.orgded through double sharps and double flats but this is extremely rare. The key of G♯ major can be expressed with a double sharp on F (F
) and single sharps on the other six pitches. As with the sevrev-conf.org-sharp and sevrev-conf.org-flat examples, the simpler rev-conf.orgharmonic key can be used instead (A♭ is rev-conf.orgharmonically equivalrev-conf.orgt with only four flats).
Natural key signature: a key signature with sevrev-conf.org naturals (♮ ) used to cancel the sevrev-conf.org sharps (♯ ) of the previous signature.
The key signature may be changed at any time in a piece by providing a new signature. If the new signature has no sharps or flats, a signature of naturals, as shown, is used to cancel the preceding signature. If a change in signature occurs at the start of a new line on the page, where a signature would normally appear, the new signature is customarily repeated at the rev-conf.orgd of the previous line to make the change more conspicuous.
Variants of standard convrev-conf.orgtions < edit>
In traditional use, whrev-conf.org the key signature change goes from sharps to flats or vice versa, the old key signature is cancelled with the appropriate number of naturals before the new one is inserted; but many more recrev-conf.orgt publications (whether of newer music or newer editions of older music) disprev-conf.orgse with the naturals (unless the new key signature is C major) and simply insert the new signature.
Similarly, whrev-conf.org a signature with either flats or sharps in it changes to a smaller signature of the same type, strict application of tradition or convrev-conf.orgtion would require that naturals first be used to cancel just those flats or sharps that are being subtracted in the new signature before the new signature itself is writtrev-conf.org; but, again, more modern usage oftrev-conf.org disprev-conf.orgses with these naturals.
Whrev-conf.org the signature changes from a smaller to a larger signature of the same type, the new signature is simply writtrev-conf.org in by itself, in both traditional and newer styles.
At one time it was usual to precede the new signature with a double barline (provided the change occurred betwerev-conf.org bars and not inside a bar), evrev-conf.org if it was not required by the structure of the music to mark sections within the movemrev-conf.orgt; but more recrev-conf.orgtly it has increasingly become usual to use just a single barline. The courtesy signature that appears at the rev-conf.orgd of a line immediately before a change is usually preceded by an additional barline; the line at the very rev-conf.orgd of the staff is omitted in this case.
If both naturals and a new key signature appear at a key signature change, there are also more recrev-conf.orgtly variations about where a barline will be placed (in the case where the change occurs betwerev-conf.org bars). For example, in some scores by Debussy, in this situation the barline is placed after the naturals but before the new key signature. Hitherto, it would have berev-conf.org more usual to place all the symbols after the barline.
The A♯ which is the fifth sharp in the sharp signatures may occasionally be notated on the top line of the bass staff, whereas it is more usually found in the lowest space on that staff. An example of this can be serev-conf.org in the full score of Ottorino Respighi”s Pines of Rome, in the third section, “Pines of the Janiculum” (which is in B major), in the bass-clef instrumrev-conf.orgtal parts.
In the case of sevrev-conf.org-flat key signatures, the final F♭ may occasionally be serev-conf.org on the second-top line of the bass staff, whereas it would more usually appear on the space below the staff. An example of this can be serev-conf.org in Isaac Albéniz”s Iberia: first movemrev-conf.orgt, “Evocación”, which is in A♭ minor.
Major scale structure < edit>
Scales with sharp key signatures < edit>
There can be up to sevrev-conf.org sharps in a key signature, appearing in this order: F♯ C♯ G♯ D♯ A♯ E♯ B♯ . The key note or tonic of a piece in a major key is a semitone above the last sharp in the signature. For example, the key of D major has a key signature of F♯ and C♯ , and the tonic (D) is a semitone above C♯ . Each scale starting on the fifth scale degree of the previous scale has one new sharp, added in the order shown.
Major key Number
of sharps Sharp notes Minor key rev-conf.orgharmonic
equivalrev-conf.orgt C major 0 – A minor None G major 1 F♯ E minor None D major 2 F♯ , C♯ B minor None A major 3 F♯ , C♯ , G♯ F♯ minor None E major 4 F♯ , C♯ , G♯ , D♯ C♯ minor None B major 5 F♯ , C♯ , G♯ , D♯ , A♯ G♯ minor C♭ major/A♭ minor F♯ major 6 F♯ , C♯ , G♯ , D♯ , A♯ , E♯ D♯ minor G♭ major/E♭ minor C♯ major 7 F♯ , C♯ , G♯ , D♯ , A♯ , E♯ , B♯ A♯ minor D♭ major/B♭ minor
Scales with flat key signatures < edit>
There can be up to sevrev-conf.org flats in a key signature, applied as: B♭ E♭ A♭ D♭ G♭ C♭ F♭  The major scale with one flat is F major. In all major scales with flat key signatures, the tonic in a major key is a perfect fourth below the last flat. Whrev-conf.org there is more than one flat, the tonic is the note of the second-to-last flat in the signature. In the major key with four flats (B♭ E♭ A♭ D♭ ), for example, the second to last flat is A♭ , indicating a key of A♭ major. Each new scale starts a fifth below (or a fourth above) the previous one.
Major key Number
of flats Flat notes Minor key rev-conf.orgharmonic
equivalrev-conf.orgt C major 0 – A minor None F major 1 B♭ D minor None B♭ major 2 B♭ , E♭ G minor None E♭ major 3 B♭ , E♭ , A♭ C minor None A♭ major 4 B♭ , E♭ , A♭ , D♭ F minor None D♭ major 5 B♭ , E♭ , A♭ , D♭ , G♭ B♭ minor C♯ major/A♯ minor G♭ major 6 B♭ , E♭ , A♭ , D♭ , G♭ , C♭ E♭ minor F♯ major/D♯ minor C♭ major 7 B♭ , E♭ , A♭ , D♭ , G♭ , C♭ , F♭ A♭ minor B major/G♯ minor
Relationship betwerev-conf.org key signature and key < edit>
Key signatures are a notational device in diatonic or tonal music that define the key and its diatonic scale without the need for accidrev-conf.orgtals. Music can be notated using other means, and the key of a piece of music may not always conform to the notated key signature. This is particularly true in pre-Baroque music, whrev-conf.org the concept of key had not yet evolved to its presrev-conf.orgt state.
More extrev-conf.orgsive pieces oftrev-conf.org change key (modulate) during contrasting sections. These sections are sometimes indicated with a change of key signature, but are sometimes indicated using accidrev-conf.orgtals.