There are the adhesive interaction parameters influence between soft polymer and steel layers to the velocity of the longitudinal sound wave in this paper. Numerical and experimental tests of the sound speed in two composite and one polymer samples are considered. The mixture formula was used to determine the elastic parameters in numerical calculations with contact layer. The model, which included the contact layer, allows calculating the layered composites elastic modulus with certain geometric and mechanical parameters of adhesive interaction. Authors have compared the results of numerical calculations and physical experiment. It was found that the adhesive interaction parameters in the calculation of layered structures is necessary to consider because the adhesive connecting polymer layers with the steel layers have experience comprehensive stretching which affects to the elastic and acoustic parameters of the samples.