There are various approaches in the contemporary classical music of the 21st century. Especially in the post-musique concrète instrumentale sound relationships and inner characteristics of the sounds define the formal and textural structure of the music (Lachenmann, 1996: 1). This article will explore the sound relationships of Onur Dülger's music, which contains many different materials. Finding the correlation of different sound materials will enable to understand the composition principles of Dülger's music. For this purpose, the composer's music named The Potbelly Hill was chosen. The reason for choosing this music is the assumption that the work can clearly show Dülger's approach to sound-based composition. Firstly, different sound sources were categorized, and then the locations and usage of these sounds in the work were investigated, and what features were paid regard while structuring the work, and how these sounds changed and developed were analyzed. Moreover, the relationship between the usage of sounds in the work and its title and program notes was examined. The results show that there are clear structural sound relationships in this work, which in some cases similar and in others complementary properties. Sounds with different features were used in different form sections in order to indicate the relationship of the work with the historical ruin named Göbeklitepe in music as stated in the program notes. It is seen that Dülger uses sounds to create contrasting and supportive musical textures according to their internal features. Each sound in the work has its own line of development in relation to other sounds. For these reasons, it can be said that Dülger uses sounds as developing objects.