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A pitch constellation is a graphical representation of pitches used to describe musical scales, modes, chords or other groupings of pitches within an octave range.〔Slonimsky 1947, .〕〔Burns 1999, .〕〔Lerdahl 2001, .〕 It consists of a circle with markings along the circumference or lines from the center which indicate pitches. Most pitch constellations use of a subset of pitches chosen from the twelve pitch chromatic scale. In this case the points on the circle are spaced like the twelve hour markings on an analog clock where each tick mark represents a semitone. ==Scales and modes== The pitch constellation provides an easy way to identify certain patterns and similarities between harmonic structures. For example. * A major scale consists of a circle with markings at 0 (or 12), 2, 4, 5, 7, 9 and 11 o'clock. * A minor scale consists of a circle with markings at 0 (or 12), 2, 3, 5, 7, 8 and 10 o'clock. The diagrams above show the two scales marked with "scale degrees". It can be observed that the tonic, second, fourth and fifth are shared, while the minor scale flattens the third, sixth and seventh notes relative to the major scale.〔Glaser 1999, .〕 Another observation is that the minor scale's constellation is the same as the major scale, but rotated +90 degrees. In the following drawing all of the major/minor scales are drawn. Note that the constellation for all the major scales or all the minor scales are identical. The different scales are generated by rotating the note overlay. The notes that need to be sharpened/flattened can be easily identified. Moreover, if we draw all seven diatonic modes we can see them all as rotations of the Ionian mode.〔〔Yamaguchi 2006, .〕 Note also the significance of the 6 o'clock point. This corresponds to a tritone. The modes including pitches a tritone from the tonic (Locrian and Lydian) are least used. The 5 o'clock and 7 o'clock pitches are also important points corresponding to a perfect fourth and perfect fifth respectively. The most used scales/modes - major (Ionian mode), minor (Aeolian mode) and Mixolydian - include these pitches. Symmetric scales have simple representations in this scheme. More exotic scales - such as the pentatonic, blues and octatonic - can also be drawn and related to the common scales. A more complete list of musical scales and modes 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pitch constellation」の詳細全文を読む スポンサード リンク
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