[en] Phase separation kinetics and growth of the new phase in supersaturated superfluid ³He-⁴He solutions was studied using the method of continuous change of ³He concentration in situ and developed theory. Simultaneous measurements of the first sound velocity and the dielectric constant were carried out during the change of concentration. The velocity and attenuation of the first sound and the dielectric constant in supersaturated metastable solutions were calculated on the assumption that the excess ³He in the solution is in the form of both atoms and droplets of the new phase. It was shown that the sound velocity, unlike the dielectric constant, is very sensitive to the formation of droplets. Comparison of the theory and the experimental data allowed the authors to elucidate the growth dynamics of the nuclei of the new phase from the metastable supersaturated mixture