We performed experimental and computational studies of the acoustic transfer power coefficient for carbon steel cylindric bars placed in axial magnetic field. By experiment, the transmission coefficients of velocity were measured for ferromagnetic bars during the first magnetization curve below saturation. Using the magnetic and magnetostriction material measurements we obtained the profile of the magnetostriction along the distance for a ferromagnetic cylindrical rod placed in a magnetic field parallel with its axis. The data were compared with numerical results obtained by computer simulation, under the assumption of spatial dependent acoustic impedance and phase velocity, leading to the conclusion that the Young modulus is affected by the magnetoelastic interaction according to a linear decrease.