The article presents a critical insight into the concepts of sound expression in documentary films by Viktor Kosakovsky, an ace of Russian modern documentary filmmaking. All the happenings in his films integrating fiction and nonfiction are in a way directed by real life. He makes use of cinematic reality as a medium for presenting his philosophy. V. Kosakovsky’s works widely screened at international film festivals and time and again Oscar nominees, are notable for their imagery, symbolism and particular sound intonation.The relevance of the present study stems from the fact that modern techniques used in sound engineering of feature documentaries are insufficiently explored, for all that modern sound technologies open up far larger expressive opportunities for the author’s brainchild.Thus, Viktor Kosakovsky in each film applies pioneer techniques pushing boundaries of classical ideas about the sound solutions in documentary filmmaking. An important aspect of the science-based research of the subject is the specification of trending techniques of the sound partition shaping in modern sound design of documentaries. The scientific novelty of the essay is provided by theoretical and case study of the filmographic material with regard to the artistic importance of sound design.The films under review were chosen so as to demonstrate the best sound solutions involving the use of specific techniques. The author concludes that for Kosakovsky work with soundscape is a major asset to developing his own style of revealing the film footage. By means of inventive sound patterns joined to the common documentary shooting technique based on observation the director finds new ways of presenting the real world.