Abstract
An equation to estimate requisite sound pressure level for ultrasonic levitation of a sample in the standing wave field has been formulated and shown to be in good agreement with experimental data. The requisite sound pressure depends not on the weight of a sample but on its density. The squared requisite sound pressure is proportional to the density of a sample and inversely proportional to the frequency of sound. Flow visualization experiments have shown that acoustic streaming is generated in the standing wave field in a cylinder when the sound pressure level is high.