What does infrasonic mean?
Infrasonic describes sound or related vibrations whose frequencies are below the lower limit of human hearing, generally around 20 hertz. Such signals cannot normally be heard directly, but they may be detected with specialized instruments and can travel over considerable distances. The word is especially common in scientific contexts involving earthquakes, volcanic activity, explosions, weather, and animal communication. Elephants, for example, communicate with low-frequency infrasonic rumbles that can carry much farther than ordinary vocalizations. Infrasonic may also function as a noun, although the adjective is more frequent. It should not be confused with ultrasonic, which refers to frequencies above the human hearing range, or with subsonic, which is often used for aircraft or other motion below the speed of sound. The term is precise and useful when discussing acoustic signals that are real and measurable but outside ordinary human perception.
Relating to sound waves or mechanical vibrations with frequencies below the normal hearing range of humans, usually below 20 hertz.
"The observatory monitored infrasonic waves generated by a large volcanic eruption."
The adjective is the common form and is used in technical, scientific, and specialist reporting.
A sound or vibration occurring below the normal hearing range of humans.
"Researchers detected a faint infrasonic originating near the fault."
The noun is comparatively uncommon and is usually found in specialist writing.
The plural is used for infrasonic sounds or waves, especially in technical writing.
"The network recorded several infrasonics associated with distant blasting operations."
Elephants use infrasonic rumbles to communicate over distances that ordinary sounds could never carry.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does infrasonic come from?
Infrasonic was formed in English during the 20th century by combining the Latin-derived prefix infra-, meaning “below,” with sonic, from Latin sonus, meaning “sound.” The compound follows the same pattern as ultrasonic and supersonic, but designates frequencies below rather than above the human hearing range. Its two elements remain evident in related terms such as infrared, infrastructure, and sonority.
Related word forms
How infrasonic is actually used
Infrasonic is primarily technical or scientific. It is most often used in discussions of acoustics, seismology, atmospheric monitoring, animal communication, and explosions; the noun form is less common than the adjective.
Easily confused with infrasonic
Both can describe frequencies below human hearing, but infrasonic specifically emphasizes extremely low-frequency sound, while subsonic is also widely used for aircraft or motion below the speed of sound.
Infrasonic is primarily an adjective describing sound in the infrasonic range, whereas infrasound is the usual noun for that sound or the phenomenon more generally.