  We introduce a description of sound waves using the phonon field equivalent
to a 4 dimensional second-rank tensor of distortion similar to electromagnetic
waves, which are described by a 4-vector of the electromagnetic field. The
exact wave solutions of the state equations of the Kadi\'c-Edelen Lagrangian
are obtained for the phonon field in a continuous isotropic medium. We
demonstrate that the state of the medium with the phonon field is analogous to
the self-consistent superconducting state of the electromagnetic field
described by the London equation. It is shown that the energy density of the
phonon field in the air is proportional both to the quares of pressure and of
frequency, which corresponds to the experimental Fletcher-Munson curves.
