Infrasound

Intermediate

Sound below 20 Hz from earthquakes and large animals.

Frequencies below 20 Hz are produced by earthquakes, volcanoes, whales and elephants. They travel long distances with little absorption.

Worked example

Elephants communicate over kilometres.

Common mistake

Can cause unease at high levels.

In more detail

Infrasound is sound below about 20 Hz, which humans usually cannot hear. Natural sources include earthquakes, volcanoes and ocean waves.

Scientists detect nuclear tests and volcanic eruptions using infrasound sensors.
Elephants communicate over long distances with infrasound.
Some animals such as elephants communicate using infrasound, which travels far through the ground and air.

Can infrasound affect people?

Strong infrasound can cause discomfort, but its effects are debated.

How far can it travel?

Very far, since its low frequency means little absorption in air.

Can humans feel infrasound?

Sometimes. Strong infrasound can cause a sensation of pressure or unease even when it is not heard as a tone.