He continued his Composition studies with Michael Jarrell at University of Music and Performing Arts Vienna and attended Composition courses with Beat Furrer und Hanspeter Kyburz in Graz.
Sijarić has been commissioned to write compositions by the Konzerthaus, Vienna Gesellschaft Wien, Konzerthaus Berlin, Collegium Novum Zürich, Wiener Musikverein,[1] Kammaransemblen Stockholm, Forum Alpbach Austria, Ensemble Cantus Zagreb, Pre Art Zürich,[2] Ensemble Zeitfluss,[3] Manhattan String Quartet,[4][5] among others.
His music was performed at many international music festivals, such as Kopenhagen - Kulturhuaptstadt Europas, Wien Modern, Salzburger Festspiele,[6] Music Biennale Zagreb,[7] Muskiprotokoll Graz,[8] Culturscapes Basel,[9] Chamber Music Festival Sarajevo and many others, in Austria, Bosnia and Herzegovina, Czech Republic, Denmark, Croatia, Italy, Republic of Macedonia, Germany, Poland, Romania, USA (Carnegie Hall),[10] Serbia, Sweden, Switzerland, Ireland.
It can be understood as presumed system of artificial sound spectrum organization and of apabsolute micro-sound (or partial) stability, which represents the opposite to the nature (or behavior) of noise.
Influenced by composers such as Beat Furrer, Gérard Grisey, Morton Feldman and research in the field of Philosophy, Semiology, Psychoacoustics and Electronic & Computer Music (using Computer as Composition Assistant), he developed his own compositional style.