17 equal temperament
In music, 17 equal temperament is the tempered scale derived by dividing the octave into 17 equal steps. Each step represents a frequency ratio of, or 70.6 cents.
17-ET is the tuning of the regular diatonic tuning in which the tempered perfect fifth is equal to 705.88 cents, as shown in Figure 1.
History and use
Alexander J. Ellis refers to a tuning of seventeen tones based on perfect fourths and fifths as the Arabic scale. In the thirteenth century, Middle-Eastern musician Safi al-Din Urmawi developed a theoretical system of seventeen tones to describe Arabic and Persian music, although the tones were not equally spaced. This 17-tone system remained the primary theoretical system until the development of the quarter tone scale.Notation
Easley Blackwood Jr. created a notation system where sharps and flats raised/lowered 2 steps, identical to ups and downs notation for 17-EDO.This yields the chromatic scale:
Quarter tone sharps and flats can also be used, yielding the following chromatic scale: