What does infrasound mean?
Infrasound is sound with frequencies below approximately 20 hertz, beneath the normal range of human hearing. It can be produced by natural events such as earthquakes, volcanic eruptions, avalanches, tornadoes, and large ocean waves, as well as by machinery and other human activities. Although people may not hear infrasound directly, they may perceive it as a sensation of vibration, pressure, or unease. Sensitive instruments can record it at great distances because low-frequency sound can travel efficiently through the atmosphere and through solid materials. The term is used in scientific fields including geophysics, seismology, meteorology, acoustics, and animal communication. Infrasound is distinct from ultrasound, which consists of sound above the human hearing range. Although usually inaudible, it has become familiar in popular discussion as a possible source of unsettling sounds associated with natural disasters, earthquakes, and unusual environmental phenomena.
nounSound with frequencies below about 20 hertz, generally below the range of human hearing. Infrasound may be detected by specialized instruments and can sometimes be felt as vibration.
- Sound with frequencies below approximately 20 hertz, usually inaudible to people but capable of being detected by instruments or sensed as vibration.
"The eruption produced infrasound that was recorded by monitoring stations thousands of kilometres away."
"Researchers identified infrasound from a distant volcanic eruption."
"The wind turbine generated a low-frequency infrasound that disturbed nearby residents."
The plural is uncommon; singular or mass usage is normally preferred. Use the plural for distinct recorded events or sources of infrasound.
"Researchers compared infrasounds recorded by stations in several countries."
Earthquakes, volcanoes, and even large ocean waves can send infrasound travelling around the world.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does infrasound come from?
The word is a compound of the Latin-derived prefix infra-, meaning “below,” and the English word sound. The same prefix appears in words such as infrared, infrastructure, and infinitesimal. Infrasound developed as a technical term for acoustic frequencies below the conventional lower limit of human hearing.
How infrasound is actually used
Infrasound is primarily a scientific and technical term. It is commonly used in geophysics, atmospheric studies, acoustics, and wildlife monitoring, while popular accounts sometimes use it for eerie or ominous low-frequency sounds.
Easily confused with infrasound
Infrasound has frequencies below the usual human hearing range, whereas ultrasound refers to sound above it.