Scale

Scale (Italian scala, “ladder”), the arrangement, by rising or falling pitch sequence, of the notes used in a musical system. The sound character of a given scale depends on the size and sequence of the intervals between its successive notes.

Since at least medieval times the typical scales of Western music have been diatonic scales, which can be illustrated by the white notes of the piano. These scales have a repeating sequence of semitones (on the white notes, E-F and B-C), and whole tones (between all other adjacent tones); and they have seven notes per octave (the eighth note in such a series is simply the repetition of the first note an octave higher). The major and minor scales that have dominated Western music since about 1650 are, strictly speaking, two modes of the basic diatonic scale: the Ionian mode, exemplified by C D E F G A B (C), which became the major scale; and the Aeolian mode, exemplified by A B C D E F G (A), which became the minor scale. The two modes sound different because the half-steps occur at different places in each. The modes of medieval and folk music are similarly formed, but with different starting points (D-D, G-G, etc.). A mode is in a certain sense a scale, but “scale” is a less complex concept. The essential part of the major or minor scale or mode is its characteristic interval pattern, which can be reproduced at any pitch, for example, G A B C D E F-sharp (G). To do so, extra notes beyond the original seven must be brought in (here, F-sharp; on the piano, a black note).

As the major-minor system of tonality developed, the natural minor scale underwent two modifications. A strong tendency to have a semitone reach upwards to the keynote (e.g. G-sharp to A) resulted in the harmonic minor scale: A B C D E F G-sharp (A). Its new “leading note” (here, G-sharp), however, created an awkward interval (here, F to G-sharp) that was disliked in melodies. The melodic minor scale in its ascending form smoothed out the offensive interval by sharpening a second note—A B C D E F-sharp G-sharp (A)—and, needing no leading note in its descending form, retained the descending natural minor scale—A G F E D C B (A).

By the late 19th century, because of the ever-increasing use of sharpened and flattened notes, Western music was based not on diatonic scales, but on a chromatic scale: 12 notes within the octave, all a semitone apart—C C-sharp D D-sharp E F F-sharp G G-sharp A A-sharp B (C). Many composers have experimented with other scales, such as the whole-tone scale—C D E F-sharp G-sharp A-sharp (C)—and microtonal scales (using intervals smaller than a semitone). Pentatonic, or five-note, scales, found in much folk and non-Western music, normally mix minor third intervals (D-F, E-G, A-C, etc.) with whole tones: C D F G A (C) or C D E G A (C). Many other scales exist, including heptatonic (six-note) scales and pentatonic scales with semitones. Many non-Western scales, however, use different tuning systems in which intervals do not correspond exactly with any interval in Western scales. An example of this is Indonesian music, which uses (among many others) a pentatonic scale called sléndro, in which the five notes are spaced almost equally within the octave.