The shear wave velocity in the medium with void pores coincides with that of the elastic medium without pores but there are two longitudinal waves in the medium with void pores in contrast to one such wave in the elastic medium. Both the waves attenuating in the way of propagation are dispersive. At a large frequency the longitudinal waves of the first kind coincide with the wave speed of dilatation wave of elastic medium and those of the second kind coincide with the velocity of the wave carrying a change of the void fraction. It is observed that the dilatational wave of the first kind does not exist at low frequency and starts its appearance at a certain frequency depending upon the void parameters of the medium. The dilatational wave of the second kind is observed to propagate at a speed less than the classical wave speed in an elastic medium. It is also shown that resonance may occur at a certain frequency depending upon the void parameters and as a result the medium may get fractured due to propagation of waves. In the absence of void pores it has been shown that the dilatational wave velocity coincides with the classical wave velocity of the elastic medium.