Diatonic scale are major scales (those with a major third/triad: Ionian, Lydian, and Mixolydian), three are minor (those with a minor third/triad: Dorian, Phrygian, and Aeolian). To these may be added the seventh diatonic scale, with a diminished fifth above the reference note, the Locrian scale. These could be transposed not only to include one flat in the signature (as described by Glarean), but to all twelve notes of the chromatic scale, resulting in a total of eighty-four diatonic scales. The modern musical keyboard originated as a diatonic keyboard with only white keys. The black keys were progressively added for several purposes:
Acoustic scale major sixth (D and A). Lendvai described the use of the "acoustic system" accompanying the acoustic scale in Bartók's music, since it entails structural characteristics such as symmetrically balanced sections, especially periods, is contrasted with his use of the golden section. In Bartók's music, the acoustic scale is characterized in various ways including diatonic, dynamic, tense, and triple- or other odd-metered, as opposed to the music structured by the Fibonacci sequence which is chromatic, static, relaxed, and duple-metered. Another way to regard the acoustic scale is that it occurs as a mode of the melodic minor scale, starting on the