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In music theory, an enharmonic scale is "an () gradual progression by quarter tones" or any "() scale proceeding by quarter tones".〔 The enharmonic scale uses dieses (divisions) nonexistent on most keyboards,〔John Wall Callcott (1833). ''A Musical Grammar in Four Parts'', p.109. James Loring.〕 since modern standard keyboards have only half-tone dieses. More broadly, an enharmonic scale is a scale in which (using standard notation) there is no exact equivalence between a sharpened note and the flattened note it is enharmonically related to, such as in the quarter tone scale. As an example, F and G are equivalent in a chromatic scale (the same sound is spelled differently), but they are different sounds in an enharmonic scale. See: musical tuning. Musical keyboards which distinguish between enharmonic notes are called by some modern scholars enharmonic keyboards. (The enharmonic genus, a tetrachord with roots in early Greek music, is only loosely related to enharmonic scales.) Consider a scale constructed through Pythagorean tuning. A Pythagorean scale can be constructed "upwards" by wrapping a chain of perfect fifths around an octave, but it can also be constructed "downwards" by wrapping a chain of perfect fourths around the same octave. By juxtaposing these two slightly different scales, it is possible to create an enharmonic scale. The following Pythagorean scale is enharmonic: In the above scale the following pairs of notes are said to be enharmonic: * C and D * D and E * F and G * G and A * A and B In this example, natural notes are sharpened by multiplying its frequency ratio by 256:243 (called a limma), and a natural note is flattened by multiplying its ratio by 243:256. A pair of enharmonic notes are separated by a Pythagorean comma, which is equal to 531441:524288 (about 23.46 cents). ==Sources== 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「Enharmonic scale」の詳細全文を読む スポンサード リンク
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