This paper presents interdisciplinary research on post-tonal orchestral music of the Estonian composer Erkki-Sven Tüür (b. 1959). In his formal thinking, Erkki-Sven Tüür belongs to the group of composers who, while using modern language, preserve classical form principles in their music. Tüür’s music is primarily based on the unfolding of musical texture, where the main development method is the conversion of one type of texture to another. There are three main types of texture in Tüür’s music: (1) a sound-centered texture, (2) a me- lody- or line-centered texture, and (3) a rhythm-centered texture. On account of that, the authors analyse the vectorial style string orchestra piece “Flamma” (2011). Our goal is to better understand the complexity of the mu- sic through discovering the structural function of musical texture and form using several different approaches in the domains of music theory, music perception and empirical, and computational music analysis. We approach Tüür’s compositional writing from two complementary facets: the symbolic side — musical score, and the esthesic side — recording. We ground our analysis on theoretical considerations about his use of musical form. In the symbolic side, we define a log of the string orchestra’s resources (e. g., vl. ord., vc. ord., vl. s.p., ...) prescribed by Tüür, segment the score based on their coordination, and (by adapting aspects of the mathematical “Theory of partitions” (Andrews 1984; Gentil-Nunes 2009) assess how diversely the resources are distri- buted along the segments and how much uniformity is found along the texture’s polyphonic lines. In the esthesic side, slider controllers (N=10) and manual indication (N=5) were used to indicate and delineate the musical tension as perceived by the participants. The ensuing data is analysed by reduction algorithms of the tension curves (such as Morris’s (1993) melodic contour reduction, DBSCAN (Ester, Kriegel, Sander, Xu 1996), and a Max/MSP flexible time-window extraction patch (2019)) in relation to musical form. The form of Tüür’s works can be described as rotational and teleological. Often, his works begin with a relatively complete process (initial rotation). Then this pro- cess is retraced several times with some additions and elaborations which can also display rotational design (sub-rotations). As a result, the structures appear that can be associated with classical formal archetypes — e. g. sonata form and sonata cycle.