In the course of the twentieth century, three separate theories on intervals and scales of Persian music have been proposed. The first of these, put forward in the 1920s by Ali Naqi Vaziri, identifies a 24-quarter-tone scale as the basis for Persian music. A second theory was formulated in the 1940s by Mehdi Barkešli according to which Persian music is defined within a 22-tone scale. The third view, arrived at by the present writer, isolates five intervals with which all modes are constructed and no longer recognises a ‘basic scale’ concept. In the following each of these three theories is explained and examined.

The 24-quarter-tone scale

The notion of the division of the scale into intervals of equal size has been the outcome of a western musical orientation. The fact that the European classical tradition, in its pursuit of a versatile technique of harmony, had developed the equal temperament, captured the imagination of those Middle Eastern musicians who came in contact with it. These musicians viewed the absence of harmony in their own music as a sign of its inferiority to western music. The desired musical advancement was thought possible only through the adoption of western harmonic practice. That, in turn, required equidistant tones.

There was a general awareness that the whole-tone and the semi-tone alone were not able to represent eastern music, which contained intervals unmistakably different from these two.