Key (music)
This article is about musical greatness. See also: Key Festival or A man for every key.
The articles Key and Key signature overlap thematically. Information that you are looking for here can therefore also be found in the other article.
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Within the framework of major-minor tonality, which has been established since about 1600, a key is determined by the identification of the tone (in European music usually major or minor) with its accidental and the fundamental of the scale used, and thus the harmonic relationship.
Example: Major key with root D results in the key of D major.
The conceivable alternative definition via the determination of the fundamental and type of scale used would be problematic, because the three different forms of the minor scale (natural, melodic, harmonic) correspond not to three, but only to one minor key. The tonal gender is therefore more decisive than the structure of the scale.
However, this only applies as long as the traditional major-minor system is not abandoned. If, for example, modal scales are included, the ratios change.
Key relationships in pieces of music
Tonal pieces of music are in a particular key, that is, their most important sections (especially the ending, and often the beginning) are composed in that key. Using methods such as modulation and regression, the keys can change within a piece, usually returning to the main key at some point. This key therefore usually dominates within the piece and thus helps to determine its character.
The key of a piece can be transposed as a whole by choosing a different root and shifting all the notes of the piece at the same distance from the original notes, so that their intervals to each other and thus the tonal gender remain unchanged. This therefore does not change the essential character of the piece. Transposing is customary and legitimate, for example in order to adapt a piece to the vocal pitch of singers or the basic tuning of instruments. In art music, however, since about 1700 the key has often been explicitly specified and mentioned in the name of the piece; thus the key indicated is essential for the character of the piece desired by the composer and thus for its performance. Accordingly, different non-equal temperaments are used up to the pre-classical period. In the Baroque era, moreover, several treatises were published on the respective key signature.
Notation with sign
The usual European notation is based on the seven root notes of the C major scale (a, b, c, d, e, f, g) and designates all the deviating pitches of the desired key with the aid of transposition signs (crosses or Bes). With the key signature of a piece, the steps shifted in relation to C major are also fixed from the outset, so that they are notated as accidentals at the beginning of the staff of each line and thus mark the regular unvarying shifting of these steps for the entire duration of a piece or section. In conjunction with the final note and/or chord, these accidentals thus give an indication of the key in which this piece or section is written.
The type and number of accidentals is determined by the distance of the respective key from the original key of C major, as indicated by the arrangement of all keys in the circle of fifths. Each variation of the accidentals designates a major key and the corresponding parallel natural minor key. A piece without accidentals can therefore be in C major or A minor; a piece with a cross in G major or E minor, one with a Be in F major or D minor, and so on. A reliable decision can usually only be made by looking at the final note (and/or final chord), which is almost always identical to (or contains) the root.
Modes are also notated with the aid of accidentals; here, however, certain accidentals can denote different modes depending on the root of the same tonal stock. For example, a scale with two crosses containing the notes of D major can be E Dorian from the root e, A Mixolydian from the root a, and G Lydian from the root g.
Scales other than major, natural minor and church scales - such as harmonic minor or scales from Eastern European, Jewish or Arabic music - are not notated by means of regular accidentals at the beginning of the staff, but by means of offset or resolution signs placed in front of individual notes, which deviate from the tone steps of an underlying major or minor scale. This reflects the fact that major and minor scales are regarded as the rule in modern Western music, while other types of scale are exceptions.
In free-tonal and atonal music, a global indication of accidentals at the beginning of a piece is usually dispensed with altogether.
