Synchronous Fuse Die

Sound is the form of the transmission of the mechanical vibration of an object (or energy). The so-called vibration is the material particle in the equilibrium position of the round trip movement. For example, when the drum is struck, it is on the upper and lower vibration, which is transmitted through the air medium in all directions. Ultrasonic is the vibration frequency of more than 20KHz, people in the natural environment can not hear and feel the sound.