Acoustic emissions（AE）induced by eiectric fieids have been investigated in a temperature range of 240～310K on single crystals of ferroelectric Rochelle salts. AE count rate was measured under ac electric fieids of a wide frequency range of 0.0125Hz～10kHz, and it was simultaneously measured with dielectric constants or D-E hysteresis loops．In a weak electric feild, the AE count rate diverges at the two transition temperatures of Tci=255K and Tcu=297K; the behavior quite resenbles that of the dielectric constants. In a strong electric field, on the other hand, the AE count rate increases only in the ferroelectric phase just like the befavior of the spontaneous polarization. It is found that the AE method is a powerful tool for investigation of such ferroelectric phase transitions.
Keywords：Acoustic Emission(AE), Rochelle salt, Ferroelectrics, Phase transition.