عنوان مقاله [English]
Classical Persian music is based on the Dastgah system. “Dastgahs” and “Avazes” comprise Radif. A Dastgah represents a multimodal and interconnected collection of some musical parts named Gushe. This music system has been developing during the Ghajar realm. In an analysis of Radif subjects, various factors are considered the modal characters. Three of them are more characteristic: gamut or scale of the mode, functional notes, and melodic progressions. The “changing notes” (Moteghaiier) are in the functional notes category which can present the modal character of a Gushe. There has been no account of evidence that theorizes occurring of these notes by researchers, yet. Thus, in this article, the main question is about the cause and function of them in Dastgah Homayun from Radif of Mirza-Abdollah. To address this subject, it is necessary to employ a systematic method. This method is recourse to some text of the treatise belonging to the Systematist School period. With presupposition of continuity of the concept about dissonance factors, a procedure developed by the author in this article. These dissonance factors, quadruple criteria, were proposed by Safi al-Din, with the title of “Asbab-e Tanafor.” In this topic, one of the most critical items is the perfect fourth interval. This element has various uses in the theoretical opinions of the Systematist School. The noted interval is also used in the mentioned method. Therefore, the first step was the definition of the basic scale for Dastgah Homayun. After that, the perfect fourth interval was inspected between all notes of this scale. The notes that have no perfect fourth intervallic relation with the other notes of the basic scale in treble and bass directions were named “unattached” and which have this relation just in one direction were named “semi-unattached.” In this way the second, third, and sixth notes of the Homayun scale are unattached and the fifth and seventh are semi-unattached. Concerning definitions, the Gushes of Dastgah Homayun were analyzed. The analysis was on the bases of scores that Dariush Talai has transcribed from NurAli Borumand’s revision of Radif of Mirza-Abdollah. The conclusion shows a convincing congruence in the absence of a perfect fourth interval between the scale notes and the changing notes in Gushes. The complexity of analysis comes from coincident functionality of various events in melodies, and so the affection of changing notes in successive and non-successive modulated Gushes. On the other hand, picking up the perfect fourth interval merely helped to recognize the direction of movements of the changing notes. This case is under the absence of the perfect fourth interval in the basic scale. In this situation, either the unattached and semi-unattached notes, themselves move or the counterpart moves to eliminate the absence of a perfect fourth interval. By finding out the relationship between changing notes and the basic scale of Dastgah Homayun, anyone could attribute these changes to the coalescence of the Dastgah as a multi-modal corpus. Finally, with studies of the other Radifs and Dastgahs, the information about this gender of music will be increased; hence, there will be more options to develop the music compositions on the base of Persian music essence.