Based on an oriented continuum model, a continuum approach for powders made of piezoelectric grains proposed in a previous work is applied to the study of electroacoustic echoes in resonant piezoelectric powders. The nonlinear equations obtained through this approach govern the piezoelectric oscillations and microgyration motion of each grain, as well as the global behavior of the powder and lead to the echo formation. The evaluations of the dynamical echo at 2τ and the memory echo atT+τ are presented. A memory phenomenon lying in the reorientation of grains due to a ponderomotive couple inside the powder sample is placed in evidence. The global response of the sample consists in summing up all the elementary electric polarizations associated with the piezoelectric oscillations of grains. Then the echoes are caused not only by the nonlinear interaction effects between the deformation of grains and the electric field, but also by a refocalization of collective oscillations which, after a complete dephasing period, gives a coherent signal through the inversion of the phase evolution. This continuum approach presents definite advantages over previous ones. Typical numerical values of parameters involved in this phenomenon as well as physical interpretations are given.