Musicology Annotation << Back On the definition of registers and octave modes of tanbur Abdurashidov Abduvali A. The article is devoted to the study of the problems of the pitch system of tanbur, which was the leading musical instrument in the performing practice of Shashmaqom, widespread in the territory of the modern republics of Tajikistan and Uzbekistan. The order of construction of registers and initial octave modes of this instrument is considered. The quintа-quart (sozi Rost) and quartа-quint (sozi Buzurg) interval tunings are determined, on the basis of which octave scales are formed, two types of scale are determined – penta-tetrachord and tetra-pentachord. At the same time, six of their structural varieties are substantiated: the structural varieties of doirai Rost, doirai Navo and doirai shikastai Navo belong to the penta-tetrachordal scale: doirai Buzurg, doirai Segoh and doirai Kalon belong to the tetra-pentachordal scale. The method of studying this problem was to clarify the vertical and horizontal structure of the construction of intervals in the tanbur scale. With the help of them, the boundaries of the pitch organization are established – the steps, on the basis of which, in relation to the drilled strings, consonant harmonic intervals are formed. This research method is used for the fi rst time and therefore it makes important adjustments in understanding and identifying the basics of the pitch system of tanbur, including registers and original octave scales. The scientific novelty of the work is determined by the application of the indicated method in the disclosure of the stated problem. For the first time in Russian musicology, the registers and octave modes of tanbur are considered and determined by the method of clarifying the vertical and horizontal relationships of intervals. The importance of the research topic is noted not only in the knowledge of the foundations of the sound system of the instrument, but also the foundations of building the modal system of Tajik classical music by Shashmaqom performed on it. Keywords: Shashmaqom, tanbur, register, scale, quarta, quinta, dzhur, soz, doira, Rost, Buzurg. DOI: 10.25791/musicology.4.2021.1188 Pp. 37-49.