The insensitive microphones used in the Soviet times weren’t suitable for recording diegetic sounds from a greater distance. The recordings of voices weren’t clear, lots of trivial noise. So to get a better sound quality, you’d have to hold the microphone very close to the person’s mouth.
According to sound director Ivenija Jakštaitė, big, insensitive microphones would be hidden in various objects that had to look good, non-intrusive in the frame. Dreams of Centenarians was no exception. We can see in these two frameshots that a microphone had been hidden in a gramophone.