The difference between sound waves and ultrasound

date：[2012-06-05] pk_hits：

Sound waves are the propagation form of mechanical vibration states (or energy) of objects. The so-called vibration refers to the back and forth motion of a particle of a substance near its equilibrium position. For example, after being struck, the drum surface vibrates up and down, and this vibration state propagates in all directions through the air medium, which is called sound wave. Ultrasonic waves refer to sound waves with a vibration frequency greater than 20000Hz, and their frequency per second is very high, exceeding the general upper limit of human hearing (20000Hz). People call this kind of invisible sound wave ultrasonic waves.

Ultrasound and audible sound are essentially the same, and their commonality is a mechanical vibration mode that typically propagates in an elastic medium as longitudinal waves. It is a form of energy propagation, with the difference being that ultrasound has a high frequency, short wavelength, and good beam and directionality when propagating in a straight line over a certain distance. Currently, the frequency range used for abdominal ultrasound imaging is between 2-5 megahertz, commonly between 3-3.5 megahertz (1 megahertz vibration per second is 1Hz, 1 megahertz=10 ^ 6Hz, that is, 1 million vibrations per second, and the frequency of audible waves is between 16-20000Hz).

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