Infrasound

Part of speech: noun

Definitions

  1. A type of sound that is inaudible to humans, which has frequencies below the lower limit of human audibility, and can be used in various applications like animal communication and geophysical monitoring
  2. This form of sound exists at frequencies beneath human hearing capacity, potentially impacting environments and behaviors in both nature and technology
  3. Sound waves that fall below the threshold of human hearing, often utilized in scientific research, environmental assessments, and by certain animal species for communication

Etymology: The concept of sound waves below the threshold of human hearing emerged alongside advances in acoustics and physics in the late 19th and early 20th centuries. Scientists began to recognize that sounds exist beyond the familiar audible range, both above and below it. The term infrasound specifically refers to frequencies lower than what humans can typically detect, beneath about 20 hertz. The word itself is a straightforward compound formed from the Latin prefix "infra-" meaning "below" or "beneath," combined with the English noun "sound." This prefix has long been used in scientific terminology to denote something lying beneath a certain level or threshold. Around the early to mid-20th century, as researchers explored the properties of sound waves in this lower frequency range, the term was coined to describe these inaudible vibrations. Its first recorded usage in English dates back to the 1920s or 1930s, a period when interest in ultrasonics and subaudible frequencies was growing due to applications in seismology, animal communication studies, and military technology. Unlike ultrasound, which deals with frequencies above human hearing, infrasound revealed a new domain where natural phenomena such as volcanic eruptions, earthquakes, and large animal movements could be detected and studied. Though the components of the word are simple, the adoption of this term marked an important step in expanding human understanding of the sound spectrum. It highlighted how human perception is limited and that many processes produce signals beyond our sensory capacity. Infrasound has since become a key concept in fields like geophysics, meteorology, and bioacoustics, illustrating a blend of linguistic economy and scientific discovery.