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Chromaticism (from Greek chroma, ‘colour’), in Western music, is connected with tonality. The distance between any given sound and the same sound an octave lower or higher is conventionally divided into 12 equal semitones. Those semitones, in turn, are grouped to form scales. The ‘major’ scale, rising, consists of tone, tone, semitone, tone, tone, tone, semitone. The ‘minor’ scale, rising, consists of tone, semitone, tone, tone, semitone, minor third. (1 tone = 2 semitones; 1 minor third = 3 semitones.) The same octave, if divided into regular semitones, would include 12—and the semitones that appear in the 12, but not in the scale, are the chromatic notes which ‘colour’ the scale.
The game, for composers, has always been to see how much use can be made of chromatic notes, that is, how much chromaticism can be employed. Until the late Middle Ages, chromatic notes were almost entirely forbidden: once your basic scale was established, you did not deviate from it throughout the music. However, in the late Middle Ages and Renaissance, composers began to experiment with ‘modulation’ (using chromatic notes to shift the music from one basic scale to another, ‘changing key’). At first this was small-scale and was an extremely marked effect, used mainly for colouring the meaning of the text (for example at the words, ‘he was crucified’, in the Credo of the Mass). The madrigals of Gesualdo (late 16th century) are the most consistently ‘experimental’ pieces in this style. Other composers of the time wrote ‘chromatic fantasies’ for instruments as something of a novelty.
In the late 17th century, an ‘equal temperament’ tuning method was devised, making all 12 semitones of equal value. This meant, therefore, that music could be written (and, theoretically, played) in any key at all—a fact celebrated at the time by Bach, whose ‘Well-Tuned Klavier’ consists of 48 preludes and fugues, two each in each of the major and minor keys.
From this point on, more and more use was made of chromaticism. It still remained predominantly a colouristic device, but modulation became commonplace into and out of ‘remote’ keys (that is, keys far from the ‘home’ key). In the 19th century, advances in the manufacture of instruments made it possible for orchestras to play in even the most sharp-or-flat-filled keys, and instead of actually modulating from one key to another, composers began to use chromatic notes in passing, to give new colour and expressive power to melody and harmony. By the 20th century, this process had reached the point where almost any note or combination of notes was ‘permissible’, so long as it made sense in context, and total chromaticism (in which the music is ‘in’ a home key, but can move at will through any other chromatic regions the composer chooses) led to atonality and eventually to twelve-note music. KMcL
See also intonation, tuning and temperament. |
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