What range of frequency typically indicates infrasonic sound?

Infrasonic sound refers to sound waves that have frequencies below the threshold of human hearing, which is generally considered to be around 20 Hertz (Hz). Frequencies in the infrasonic range typically fall between 0 to 20 Hz.

This range includes sounds that are lower than what humans can perceive, which can be generated by natural phenomena such as earthquakes, thunder, and large machinery. Infrasonic waves have characteristics that allow them to travel long distances and penetrate various materials, which can be useful in applications such as monitoring environmental events or conducting research in geology and seismology. Understanding the infrasonic range helps professionals in acoustics and Sonic imaging assess vibrations and sounds that go beyond the normal hearing range.

The other frequency ranges provided in the choices fall within the audible or ultrasonic spectrum, which are not considered infrasonic. While 20-200 Hz includes low-frequency sounds, it does touch the threshold of human hearing, thus disqualifying it from being strictly infrasonic.