functionality of tahrir in the construction of gushes in iranian classical music

in this article, according to the 5 transcriptions of iranian vocal masters, we try to observe some of various functions of tahrir in iranian classical music with comparative - analytic method and schenkerian analysis. the goal of usage schenkerian analysis is to interpret the underlying structure of tahrirs by showing hierarchical relationships among tones, and also drawing the graphs  of reduce analysis as the fundamental lines of tahrirs. tahrir is the main ornament in persian singing and instrumental music. in summary, tahrir is a falsetto break or cracking of the voice in the form of the grace note above, and between the notes of, the melody line. according to the research, the tahrir is not only an ordinary ornament, but rather it must be known as a structural function in iranian classical music. these transcriptions are selected from the early segment of dastgâh-e châhârgâh. generally, dastgâh is one of the twelve multi-modal cycles in iranian classical music, and also early segment of each dastgâh classically named darâmad. these transcriptions are from the records of seyyed ahmad khân, soleimân amirqâsemi, abolhasan eqbâl âzar, rezâqoli mirzâ zelli and abdollâh davâmi. in this study we will explain the mechanism of tahrir based on melodic progression (seyr). the melodic progression is one of the complicated characteristics of eastern mode that refers to the how the combination of the tones and progression the melody. indeed, the how motion of tones in tahrir-s is dependent of the seyr. in this article we will use 3 terms for explained the mechanism of tahrir-s into the texture of gushe-s (the dastgâh is composed of many melodic segments with various lengths which are called gushe): tahrir-sentence, tahrir-phrase and tahrir-motive. the tahrir-sentence is a musical sentence that is only based on tahrir. the tahrir-phrase is intermediate concept that is between the tahrir-sentence and tahrir-motive. the tahrir-motive is fundamental component of a tahrir-sentence; in other words, the tahrir-motives articulate and fractionate a tahrir-sentence. virtually, each tahrir-sentence is composed of a number of tahrir-phrase and tahrir-phrase is composed of a number of tahrir-motive. apart from following the logic of movement and stillness, the method of separation the tahrir-motives, sometimes follow the rising and falling melody and sometimes follow the pause on the important tones of the mode (such as the shâhed note that is the center around which the melody evolves and rest note on which the melodic segments comes to rest) and sometimes follow the pause similar to staccato. based on study of transcriptions and analysis charts, we will try to indicate that the gushe-s how to get in shape by the tahrir-s. hereupon, this investigation can be helped us to perceive the mechanism of gushe-s. some functions of tahrir that can be enumerated are: development and expansion of a tone or a specific modal cell; help to move from one tone to the other tone; help to modulation and also help to return to the primary mode and concluding the sentence, phrase or gushe which is called forud in dastgâhi music.