The Modal Arrangement of the Dastgāh and its Effect on the Representation of ModalEntities and the Possibility of Expanding the Repertoire; Case Study: Mokhālef-E Segāh  –Bayāt-E Isfahān-E Qadim & Nayshābūrk-E Māhūr

The logic of the Dastgāh, from its emersion to the present day, has always included a modal arrangement from a lower pitch to a higher level. This arrangement always returns to the "Darāmad" mode at the lowest pitch of the system represented by the concept of Forūd, a motion to objectify the cyclic pattern of the Dastgāh. The critical point in these modal arrangements is that some modal entities appear in different Dastgāh-hā (s. Dastgāh) with the same or sometimes different names. As a result, a single entity may occur at different pitch levels relative to the fundamental pitch of the corresponding Dastgāh in Darāmad. On the other hand, the acoustic nature of the anterior and posterior modes of a mode and the tuning of the basis of the Dastgāh affect the acoustic appeal of that mode. In this regard, a modal entity in various presentations within the arrangement of different Dastgāh-hā, in its outer layers, undergoes a kind of melodic adaptation. In addition, according to the current concept of Āvāz in Iranian classical music, the independent performance of a mode outside the system and without the presence of previous and subsequent entities, as well as the concept of Forūd will have a different timbre and tonal color. The present study uses descriptive, analytical, and comparative methods and two case studies: Mokhālef-e Segāh – Bayāt-e Isfahān-e Qadim and Nayshābūrk-e Māhūr, to study the effect of modal arrangement of the Dastgāh, on the acoustic representation of a modal entity and its mental perception in this system. Each of the four authoritative narrations of Iranian classical music Radif, including the narrations of Mirzā Abdullāh, Mirzā Hosseinqoli, Abdullāh Davāmi and Mahmūd Karimi, from micro to macro level, based on the concept of Seyir has been examined for this research. This study shows that the Dastgāh modal regulation of the device and the relative pitches within each mode are effective and important in three ways:Depending on the position of a mode in the arrangement of the Dastgāh relative to the Darāmad, the concept of Forūd will require different adjustments.Each modal entity within the framework of the Dastgāh, apart from the relation it finds with Darāmad, also sees a connection with its previous and subsequent modes and will be influenced by them.The displacement of each modal entity inside the framework of the Dastgāh will represent distinct feelings and perceptions of the Dastgāh as a Nobat-e Morattab.Considering the similarities in melody and intervals of the two Mokhālef-e Segāh – Bayāt-e Isfahān-e Qadim and Nayshābūrk-e Māhūr, these two seem to be the same entity that has two different acoustic manifestations in two different uses, creating two distinct perceptions for the listener. Also, the microstructural differences between the Mokhālef-e Segāh and the Bayāt-e Isfahān-e Qadim are due to these adaptations within or separate from the system’s framework. In general, the present study results indicate the existence of subtle changes in each of them, which leads to the expansion of repertoire at different levels.