What are Sounds too low for humans to hear?

Sounds too low for humans to hear are known as infrasound. These sounds have frequencies below 20 Hz, which is below the threshold of human hearing. Infrasound can be produced by natural events like earthquakes and volcanic eruptions, as well as man-made sources such as heavy machinery and explosions. While we cannot hear them, infrasound can still have physical effects on the body and may be sensed by animals.