超声就是普通的弹性介质的机械扳动,这种振动以一定的速度传播并且具有一定的能量。超声波——是介质的互相更替的稠密和稀疏。超声的传播速度与介质的弹性和介质的密度有关。超声波的波长,也和普通的声波一样,决定于两相隣的稠密或稀疏之间的距离。超声频率的下限 Ultrasound is the mechanical pulling of an ordinary elastic medium, which vibrates at a certain speed and has a certain amount of energy. Ultrasound - is the dense and sparse replacement of media. The propagation speed of ultrasound is related to the elasticity of the medium and the density of the medium. The wavelength of an ultrasonic wave, just like a normal acoustic wave, depends on the distance between two adjacent dense or sparse waves. Lower limit of ultrasound frequency