JIANGSU JIUJIUJIAYI ULTRASONIC TECHNOLOGY CO.,LTD

Sound wave is the object the spread of the mechanical vibration state (or energy). Vibration refers to the material of the particle movement back and forth around its equilibrium position. Raised after tapping, for example, it's up and down vibration, the vibration state of medium in all directions spread through the air, this is the sound waves.
We know that when the object vibration sound. Scientists will the number of vibrations per second is called the frequency of the sound, it is the unit of Hertz (Hz). We human ears can hear the sound wave frequency is 16 ~ 20000 hz. Therefore, when beyond a certain vibration frequency of the object, which is higher than the human ear on the threshold limit, people listen to not to come out, the sound waves is called "ultrasonic".

Generally is generally believed that in the 16 ~ 20 hz frequency sound waves is called "sound or the sound waves, sound waves called ultrasonic frequency in more than 20 KHZ.

Ultrasound and audible sound in essence is consistent, they all have in common is a kind of mechanical vibration, usually in the form of p-wave spread within the elastic medium, is a form of energy transmission, the difference is the ultrasonic frequency is high, short wavelength, within a certain distance along a straight line spread good beam and directivity. Study of ultrasonic generation, transmission, reception, and various kinds of ultrasonic effect and application of acoustic branch called ultrasonics. Generate ultrasonic device has a mechanical type ultrasonic generator (such as air whistle, whistle, and liquid whistle, etc.), using the principle of electromagnetic induction and electromagnetic effect power ultrasonic generator, and the use of the electrostrictive effect of piezoelectric crystals and magnetostriction effect of ferromagnetic material made of electroacoustic transducer, etc.