Scale (Music)



I  INTRODUCTION

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



II  DIATONIC SCALES

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 half-steps, or semitones (wherever E-F and B-C occur), and whole steps (between all other adjacent tones); and they have seven tones per octave (the eighth tone in such a series is simply the repetition of the first tone 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 major mode, exemplified by C D E F G A B (C); and the minor mode, exemplified by A B C D E F G (A). 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 tones 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 half-step reach upward to the keynote (as, G-sharp to A) resulted in the harmonic minor scale: A B C D E F G-sharp (A). Its new "leading tone" (here, G-sharp), however, created an 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 sharping a second tone-A B C D E F-sharp G-sharp (A)-and, needing no leading tone in its descending form, retained the descending natural minor scale-A G F E D C B (A).



III  NONDIATONIC SCALES

By the late 19th century, because of the ever-increasing use of sharped and flatted tones, Western music was based not on diatonic scales, but on a chromatic scale: 12 tones within the octave, all a half-step 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 half step). Pentatonic, or five-tone, scales, found in much folk and non-Western music, normally mix step-and-a-half intervals (D-F, E-G, A-C, etc.) with whole steps: C D F G A (C) or C D E G A (C). Many other scales exist, including heptatonic (six-tone) scales and pentatonic scales with half-steps.



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