When we talk about sound, sonic is what comes to our mind. The sound above the human hearing range is called ultrasonic. Humans have the ability to hear a maximum of up to a frequency of 20 KHz. The ultrasonic frequencies are more than 20 KHz.

The level of solid objects and liquids in industries is measured by ultrasonic waves. Ultrasonic level measurement is needed as it is most suitable for hot, boiling and corrosive liquid. It is based on the contactless principle which you will learn more about. The normal frequency range which is used for ultrasonic level measurements is within the range of 40 to 200 KHz.