Scale

An ordering of a system of pitches, usually in ascending frequency order. The distance between any two pitches or notes is called an interval (see interval for comparative representations).

See also: Intonation, Temperament, Tempered Tuning, Tuning.

Many types of scales are used by different cultures, varying in the number of pitches contained in the scale (such as five in pentatonic scales, seven in the western diatonic scale, and twelve in the western scale of equal temperament), and the specific pitches involved. In western usage, a scale of just intonation is based on integer frequency ratios, whereas a scale of equal temperament divides the octave into a number of equal intervals. See also: Pythagorean Scale, Appendix C.

In some cultures the notes of the scale are rigidly adhered to pitches. Melodies move from one note to another avoiding any pitches in between, as is the practice in western art music. However, in most oriental and folk music, the notes of the scale are treated as reference points, and in performance, pitches in between, which are called microtones, are often used. In Indonesian gamelan music, the metallic instruments have fixed pitches, organized according to the pelog and slendro scales, but the exact tuning of each pitch varies between orchestras.

Variations in the ordering and intervals of a scale may result in different modes, such as the major and minor modes of the western scale. The scale may be characterized by its mode, the intervals it contains, sometimes the note it begins on, and occasionally whether it is treated in ascending or descending order. It may arise from a theoretical specification, as in western music, or from the available notes on a given instrument, or from a cultural tradition (as with the Indian raga scales which are specific to the raga).