Speaker 1: Welcome to brain Stuff, a production of iHeart Radio, Hey
Speaker 1: brain Stuff, Lauren Bobo bomb Here. In the same way
Speaker 1: that ultra violet light and infrared light exist outside what
Speaker 1: the human eye can perceive, sound waves exist beyond the
Speaker 1: frequencies of what humans can hear. When those sound waves
Speaker 1: are higher frequency than what we can hear, we call
Speaker 1: them ultrasonic, and when they're lower frequency, we call them infrasonic.
Speaker 1: Several natural sources, including volcanoes, avalanches, earthquakes, and meteors, produce
Speaker 1: infrasonic waves, also called infrasound. Animals like elephants and whales
Speaker 1: may communicate with infrasound, and man made inventions like wind
Speaker 1: turbines can generate these sounds too. Detecting infrasonic waves is
Speaker 1: one of the key ways that governments can monitor for
Speaker 1: nuclear bomb tests. That's because infrasonic waves decay very slowly,
Speaker 1: and when they're large enough, they can wrap around the
Speaker 1: globe several times before dissipating. And it turns out that
Speaker 1: tornadoes can produce unique infrasonic waves even before tornado genesis,
Speaker 1: which is when the storm forms an hour or more before.
Speaker 1: Scientists have known about the tornado infrasound connection for several decades,
Speaker 1: but to learn more about this process and to better
Speaker 1: understand how humans could harness this information, a group of
Speaker 1: scientists is developing a long distance, passive way of listening
Speaker 1: in on tornadoes. In doing so, we'd be able to
Speaker 1: deal with the fact that three fourths of all current
Speaker 1: tornado warnings are false alarms and thus too often ignored
Speaker 1: or not taken seriously. Infrasound could represent another source of
Speaker 1: data to add to our arsenal one, Brian Elbing, and
Speaker 1: Oklahoma State University Mechanical and Aerospace engineering professor, said in
Speaker 1: a press release discussing this research. By monitoring tornadoes from
Speaker 1: hundreds of miles away, will be able to decrease false
Speaker 1: alarm rates and possibly even increase warning times. Elbing his
Speaker 1: team built special listening devices using microphones sensitive to low
Speaker 1: frequencies that were then placed inside of containers with noise
Speaker 1: holes and arranged in a triangle for precision measurements. The
Speaker 1: goal was to separate regular wind noise from tornado noise.
Speaker 1: Elbing said, a wind noise is incoherent, so if you
Speaker 1: average it over a large space, it will sum up
Speaker 1: to zero. Conversely, tornado infrasound is coherent, meaning waves look
Speaker 1: alike over large distances, so the pressure waves add together
Speaker 1: and contain information. This new capability could mean that storm
Speaker 1: chasers trying to gather data about tornadoes would be able
Speaker 1: to take fewer risks in their research. Imagine drones equipped
Speaker 1: with special infrasonic microphones, for instance, flying in the vicinity
Speaker 1: of storms, transmitting data to forecasters and scientists. It could
Speaker 1: therefore help save lives by giving people earlier warnings about
Speaker 1: potentially deadly storms. In the United States, tornadoes result in
Speaker 1: hundreds of deaths and billions of dollars in property damage
Speaker 1: every year. By finding these storms earlier and helping us
Speaker 1: understand how those storms form in the first place, this
Speaker 1: sort of research could allow people to get to safety
Speaker 1: and batten down the proverbial hatches. Continued work by other
Speaker 1: teams has shown that infrasound sensor arrays can detect and
Speaker 1: tracked tornadoes that are over sixty miles or KOs away.
Speaker 1: Today's episode was written by Christopher Hassiotis and produced by
Speaker 1: Tyler Klie. For more on this and lots of other
Speaker 1: sound topics, visit how stuff works dot com. Brain Stuff
Speaker 1: is production of I Heart Radio or more podcasts in
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