[en] On the basis of measurements of the first sound absorption in ³He - ⁴He solutions and the developed kinetic theory of a phonon-impurity system, the phonon spectrum dispersion is analysed in solutions with 0.15, 0.5 and 1.0% ³He concentrations at saturated vapor pressures and elevated pressures. It is found that the phonon spectrum dispersion in solutions is the same as in pure ⁴He. This finding is also supported by the analysis of other experimental results on the second sound absorption, thermal conductivity, the first soun't velocity and heat pulse propagation