Sound waves are mechanical vibration waveforms produced when sound propagates through media such as air or water.

The reason people can hear sound is precisely because the vibrations of the air reach the human ear. This vibration contains a key physical quantity—frequency.

The normal sound frequency range that the human ear can perceive is about 16Hz ~ 18,000Hz (18kHz). However, due to age and individual hearing differences, each person's actual hearing range will vary.

Ultrasound refers to sound waves with frequencies above 18kHz that are inaudible to the human ear. In industrial applications, the frequency range of ultrasound typically extends up to 10MHz.

"Ultra" + "Sonic" = Ultrasound — sounds that surpass the limits of human hearing

The frequency range of sound waves

The frequency range of everyday sounds