Propagation of normal waves in porous rod with closed pores on boundaries

Propagation of normal waves in porous cylindrical rod with closed pores on boundaries is investigated. For this medium the dispersion equation is derived. At low-frequency this equation has two roots which are velocities of the normal waves. While in the cases of elastic rod and of porous rod with opened pores there is unique low-frequence wave. At high-frequency the dispersion equation has one special root. With such velocity the Rayleigh wave propagates along free boundary of the porous medium with closed pores. In this case the Rayleigh wave can exist always.