—The paper considers the results of a series of laboratory experiments (more than 100) on the formation of synthetic sand samples containing water/ice and methane or tetrahydrofuran hydrates in the pore space and of the measurement of their acoustic properties (velocities and attenuation of acoustic waves). The main aim of the experiments was to establish the relationship between the velocities of acoustic waves and the ice or hydrate saturation of the samples. An increase in the content of ice and hydrates always leads to a velocity increase. However, the rate of the velocity increase is determined by the localization of ice and hydrates in the samples: at the contacts between the sand grains (“cementing” model) or in the pore space (“filling” model). It has been established that the “cementing” model, characterized by a drastic initial increase in velocities, works for ice or gas hydrates formed from free methane and localized in the pores. On the contrary, tetrahydrofuran hydrates form by the “filling” model and cause a slow increase in velocities.