[en] For the first time experimental observations are made of the oscillation in the intensity of the unshifted line and in the intensities of the US satellites when the γ-resonance radiation is modulated by the coherent US excitation. It is stated that the coherent US can be excited in the investigated sample if the US amplitude is transmitted homogeneously from the generator to the sample. A special sample-unit is described which provides a homogeneous transmission, and it is shown that the lifetime of the US phonons is not substantial and does not affect the oscillation of the absorption line intensities. (author)