A refrigerator includes a gas flow generator formed with passages providing communication between an annular inlet chamber and a gas flow chamber, so that gas under pressure in the inlet chamber flows through the passages into the gas flow chamber. An energy transfer tube has a cylindrical interior space in communication with the gas flow chamber at one end of the tube and a throttle valve is installed in the energy transfer tube at its opposite end. An acoustic tone at a frequency in the range between about 1 kHz and about 20 kHz is spontaneously generated in the energy transfer tube when gas at a pressure exceeding about 100 psig is supplied to the inlet chamber.