A hypothesis that hearing mechanisms must be polyfunctional in nature is substantiated. The effect of reduction in loudness of unfixated sounds is considered to be one such mechanism: besides participating in constant and non-constant perception of loudness, in localization of a sound in space, and in perception of a sound against the background of concomitant sounds, the reduction effect concerns also a number of functions characteristic of the perception of pitch. It has been experimentally shown that the capacity for perceptual abstraction of the fundamental tone out of a musical sound can be formed on the basis of preliminary development of the habit to use the above effect in perceptual acts. Development of the habit is followed by the ability to perform fine differentiations between timbers of the same pitch as the fundamental tone.