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In music theory, a diatonic scale (or heptatonia prima) is a scale composed of seven distinct pitch classes. The diatonic scale includes five whole steps and two half steps for each octave, in which the two half steps are separated from each other by either two or three whole steps, depending on their position in the scale. This pattern ensures that, in a diatonic scale spanning more than one octave, all the half steps are maximally separated from each other (i.e. separated by at least two whole steps). The word "diatonic" comes from the Greek , meaning progressing through tones.〔Ball, Philip (2010). ''The Music Instinct'', London: Vintage, p.44〕 The seven pitches of any diatonic scale can be obtained using a chain of six perfect fifths. For instance, the seven natural pitches which form the C-major scale can be obtained from a stack of perfect fifths starting from F: :F—C—G—D—A—E—B Called Pythagorean tuning, this property of the diatonic scales was historically relevant and possibly contributed to their worldwide diffusion because for centuries it allowed musicians to tune musical instruments easily by ear. Any sequence of seven successive natural notes, such as C-D-E-F-G-A-B, and any transposition thereof, is a diatonic scale. Piano keyboards are designed to play natural notes, and hence diatonic scales, with their white keys. A diatonic scale can be also described as two tetrachords separated by a whole tone. The term ''diatonic'' originally referred to the diatonic genus, one of the three genera of the ancient Greeks. In musical set theory, Allen Forte classifies diatonic scales as set form 7–35. This article does not include alternative seven-note diatonic scales such as the harmonic minor or the melodic minor. ==History== Diatonic scales are the foundation of the European musical tradition. Western harmony from the Renaissance until the late 19th century is based on the diatonic scale and the unique hierarchical relationships, or diatonic functionality, created by this system of organizing seven notes. The modern major and minor scales are diatonic, as were all of the 'church modes'. What are now called major and minor were in reality – during the medieval and Renaissance periods – only two of eight modes ('church modes') based on the same diatonic notes (but forming different scales when the starting note was changed). Depending on which of the seven notes is used as the beginning, the positions of the intervals, the half-steps, end at different distances from the starting tone, hence obtaining seven different scales or modes that are, as already mentioned, deduced from the diatonic scale. By the end of the Baroque period, the notion of musical key was established—based on a central triad rather than a central tone. Major and minor scales came to dominate until at least the start of the 20th century, partly because their intervallic patterns are suited to the reinforcement of a central triad. Some church modes survived into the early 18th century, as well as appearing occasionally in classical and 20th-century music, and later in modal jazz. 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「Diatonic scale」の詳細全文を読む スポンサード リンク
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