What frequency range defines infrasound?

Infrasound refers to sound waves that fall below the range of human hearing, which is typically defined as frequencies less than 20 Hz. This range can include various natural phenomena, such as earthquakes, volcanic eruptions, and sounds produced by large machinery. Because infrasound is below the threshold of what humans can perceive, it is important in various fields, including meteorology and geophysics, and can even impact animal behavior.

The other frequency ranges listed pertain to sounds that are audible or within the spectrum of human hearing and are not classified as infrasound. Consequently, less than 20 Hz is the accurate representation of infrasound.