Persian Music Theory
Persian art music is organized into twelve systems called Dastgah.The seven main dastgah of contemporary Persian art music are: Shur, Mahur, Homayun, Sehgah, Chahrgah, Rast Panjgah, and Nava. In addition, there are five auxiliary dastgah-ha (singular dastgah). The term Avaz (song) or Naghmeh (melody) designates these satellite systems, four belonging to the dastgah of Shur and one to Homayun. Their individual names are: Abu Ata, Bayate Tork, Afshari, and Dashti, associated with the dastgah of Shur; and Esfahan associated with Homayun. Each dastgah has its own special repertory of melodies called Gusheh-ha (singular gusheh), which embody the most characteristic aspects of the dastgah. The total number of gusheh-ha in all twelve dastgah makes up a body of music called the Radif.
- The distinctive scale of Chahargah contains two identical tetrachords, C D-koron E F and G A-koron B C, each containing a neutral second and a major third. There are also two intervals close to augmented seconds, D-koron to E and A-koron to B, not often found in Persian music. The melodic motive that identifies Chahargah is the rising neutral third to the tonic, A-koron to C. This motive is stressed at the opening and again at the cadence. The A-koron receives additional emphasis by a trill from the note below. The trill of a neutral second and a stressing of the neutral third give a particular sound to Chahargah making it one of the most easily recognizable dastgah-ha.
- The scale of Shur is similar either to the Western natural minor scale with the second degree lowered by a quarter tone or the phrygian mode with the second degree raised by quarter tone. Both the shahed and ist are the first note.
- The scale of Mahur is the same as the plagal form of the Western major. Both the shahed and ist are the first note (the note of stress, shahed, is debated among theorists).
- The scale of Homayun contains a natural second and major third in the lower tetrachord and a minor second and minor third in the higher tetrachord. The second degree is the shahed and the seventh degree is the ist.
- The scale of Esfahan is similar to the Western harmonic minor scale with the sixth degree raised a quarter tone. The shahed is the fourth degree and the sixth degree is the ist (the note of stop, ist, is debated among theorists).
- The scale of "Dastgah-e-Nava" is like a natural minor scale with a slightly raised sixth degree or half-flat. Nava is similar to the dastgah of Shur, starting on its fourth degree and bears a strong relation, as both tetrachords have the same configuration only their position is reversed. The first degree is the shahed and the sixth degree is the ist.- The scale of "Dastgah-e-Rast-Panjgah" is identical with that of Mahur, that is, the Western major scale.Rast-Panjgah is rather special as evidence of a process of evolution in the Radif. The shahed and ist are the first degree (shahed is debated among theorists).- The scale of "Dastgah-e-Segah" is problematical. When written from the tonic that is both shahed and ist has an imperfect fifth and also obscures the stressing of the neutral third below the tonic. Both of these faults are corrected if the scale is written with the shahed as the third note, which is the version given by most theorists: C D E-Koron F G A-Koron B-Flat C.- The scale of "Avaz-e-Dashti" is like a Shur scale with the third degree as ist and the fifth degree as shahed. Many folk melodies are included among the gusheh-h of Dashti.- The scale of "Avaz-e-Bayat-e-Tork" is written from the third degree of scale Shur as both shahed and ist. To relieve the tonal monotony, some musicians use the fifth degree of Bayat-e-Tork as the note of cadencing.- The scale of "Avaz-e-Afshari" is written from the seventh degree of Shur. The second degree is the ist and fourth degree is the shahed and the seventh is a decorating tone. Afshari opens on the fourth degree, stresses it heavily, and then descends.- The scale of "Avaz-e-Abu Ata" is starts on the second degree of Shur and rises to the fourth degree. The shahed is the fourth degree, and the ist is the second. The initial begging of Abu Ata features a rapid ascent of a neutral third, and an immediate descent, repeated with increasing elaboration. The melody always returns to Shur, one degree below Abu Ata's ist for final cadence.