Infrasound
Infrasound refers to sound waves with frequencies below the range of human hearing, typically considered below 20 Hz. These low-frequency sound waves can travel long distances and penetrate solid objects, making them difficult to detect and measure. Infrasound has also been used for security and surveillance; for example, infrasound sensors have been used to detect and locate hidden underground tunnels and bunkers. Infrasound is naturally produced by various sources, such as weather systems, earthquakes, volcanic eruptions, and ocean waves, and human-made sources, such as industrial machinery, transportation, and construction. Additionally, some people may be more sensitive to infrasound than others, and the effects of exposure can vary depending on the individual and the specific conditions of exposure [National Research Council].
Infrasound has been used for various scientific and practical applications. For example, in geophysics, infrasound has been used to study earthquakes and volcanic eruptions and detect and locate nuclear explosions. In meteorology, infrasound has been used to study atmospheric dynamics, including the behavior of tornadoes and hurricanes [National Oceanic and Atmospheric Administration].
In wildlife biology, infrasound has been used to study the communication patterns of elephants, whales, and other species [International Whaling Commission].
In addition, infrasound has been used in biomedical research to study the effects of exposure to low-frequency noise on human health. However, infrasound can also have adverse effects on human health and well-being. Prolonged exposure to infrasound can cause symptoms such as headaches, fatigue, and sleep disturbances [WHO].
National Research Council. (2002). Low-Frequency Sound and Marine Mammals. National Academies Press.
www.swpc.noaa.gov/phenomena/infrasound.
https://iwc.int/infrasound.
https://www.who.int/publications/i/item/9789241501369.