By applying magnetic pulses to the ferromagnetic policrystalline rods we can generate ultrasonic vibrations travelling through the sample as magnetoelastic standing waves propagating in the extensional mode. The work points out either to the measurement of the “stress sensitivity” as a function of the magnetizing field or to the Q-factor as a function of the frequency. Excellent agreement between theory and experiment is obtained. Moreover we observe a first result interesting for applications. Indeed interferential phenomena are obtained as an effect of excitation pulsewidth.