1 00:00:01,920 --> 00:00:06,360 Speaker 1: Welcome to brain Stuff, a production of iHeart Radio, Hey 2 00:00:06,400 --> 00:00:10,200 Speaker 1: brain Stuff, Lauren Bobo bomb Here. In the same way 3 00:00:10,280 --> 00:00:13,880 Speaker 1: that ultra violet light and infrared light exist outside what 4 00:00:13,960 --> 00:00:17,759 Speaker 1: the human eye can perceive, sound waves exist beyond the 5 00:00:17,800 --> 00:00:21,440 Speaker 1: frequencies of what humans can hear. When those sound waves 6 00:00:21,480 --> 00:00:23,760 Speaker 1: are higher frequency than what we can hear, we call 7 00:00:23,840 --> 00:00:28,000 Speaker 1: them ultrasonic, and when they're lower frequency, we call them infrasonic. 8 00:00:29,200 --> 00:00:34,000 Speaker 1: Several natural sources, including volcanoes, avalanches, earthquakes, and meteors, produce 9 00:00:34,040 --> 00:00:38,839 Speaker 1: infrasonic waves, also called infrasound. Animals like elephants and whales 10 00:00:39,000 --> 00:00:42,520 Speaker 1: may communicate with infrasound, and man made inventions like wind 11 00:00:42,600 --> 00:00:47,280 Speaker 1: turbines can generate these sounds too. Detecting infrasonic waves is 12 00:00:47,360 --> 00:00:49,760 Speaker 1: one of the key ways that governments can monitor for 13 00:00:49,840 --> 00:00:54,840 Speaker 1: nuclear bomb tests. That's because infrasonic waves decay very slowly, 14 00:00:55,320 --> 00:00:57,560 Speaker 1: and when they're large enough, they can wrap around the 15 00:00:57,600 --> 00:01:02,000 Speaker 1: globe several times before dissipating. And it turns out that 16 00:01:02,080 --> 00:01:07,119 Speaker 1: tornadoes can produce unique infrasonic waves even before tornado genesis, 17 00:01:07,319 --> 00:01:10,440 Speaker 1: which is when the storm forms an hour or more before. 18 00:01:11,400 --> 00:01:15,120 Speaker 1: Scientists have known about the tornado infrasound connection for several decades, 19 00:01:15,560 --> 00:01:17,880 Speaker 1: but to learn more about this process and to better 20 00:01:17,959 --> 00:01:21,399 Speaker 1: understand how humans could harness this information, a group of 21 00:01:21,400 --> 00:01:25,080 Speaker 1: scientists is developing a long distance, passive way of listening 22 00:01:25,080 --> 00:01:28,679 Speaker 1: in on tornadoes. In doing so, we'd be able to 23 00:01:28,760 --> 00:01:31,240 Speaker 1: deal with the fact that three fourths of all current 24 00:01:31,240 --> 00:01:35,039 Speaker 1: tornado warnings are false alarms and thus too often ignored 25 00:01:35,160 --> 00:01:39,360 Speaker 1: or not taken seriously. Infrasound could represent another source of 26 00:01:39,440 --> 00:01:43,680 Speaker 1: data to add to our arsenal one, Brian Elbing, and 27 00:01:43,760 --> 00:01:47,920 Speaker 1: Oklahoma State University Mechanical and Aerospace engineering professor, said in 28 00:01:47,920 --> 00:01:51,640 Speaker 1: a press release discussing this research. By monitoring tornadoes from 29 00:01:51,720 --> 00:01:54,640 Speaker 1: hundreds of miles away, will be able to decrease false 30 00:01:54,640 --> 00:02:00,160 Speaker 1: alarm rates and possibly even increase warning times. Elbing his 31 00:02:00,280 --> 00:02:04,360 Speaker 1: team built special listening devices using microphones sensitive to low 32 00:02:04,400 --> 00:02:07,919 Speaker 1: frequencies that were then placed inside of containers with noise 33 00:02:07,960 --> 00:02:11,680 Speaker 1: holes and arranged in a triangle for precision measurements. The 34 00:02:11,720 --> 00:02:15,200 Speaker 1: goal was to separate regular wind noise from tornado noise. 35 00:02:16,200 --> 00:02:19,480 Speaker 1: Elbing said, a wind noise is incoherent, so if you 36 00:02:19,520 --> 00:02:21,800 Speaker 1: average it over a large space, it will sum up 37 00:02:21,800 --> 00:02:27,240 Speaker 1: to zero. Conversely, tornado infrasound is coherent, meaning waves look 38 00:02:27,240 --> 00:02:30,720 Speaker 1: alike over large distances, so the pressure waves add together 39 00:02:30,919 --> 00:02:35,720 Speaker 1: and contain information. This new capability could mean that storm 40 00:02:35,760 --> 00:02:38,840 Speaker 1: chasers trying to gather data about tornadoes would be able 41 00:02:38,880 --> 00:02:42,960 Speaker 1: to take fewer risks in their research. Imagine drones equipped 42 00:02:42,960 --> 00:02:46,560 Speaker 1: with special infrasonic microphones, for instance, flying in the vicinity 43 00:02:46,600 --> 00:02:51,480 Speaker 1: of storms, transmitting data to forecasters and scientists. It could 44 00:02:51,600 --> 00:02:55,040 Speaker 1: therefore help save lives by giving people earlier warnings about 45 00:02:55,080 --> 00:02:59,040 Speaker 1: potentially deadly storms. In the United States, tornadoes result in 46 00:02:59,120 --> 00:03:01,920 Speaker 1: hundreds of deaths and billions of dollars in property damage 47 00:03:02,000 --> 00:03:05,680 Speaker 1: every year. By finding these storms earlier and helping us 48 00:03:05,720 --> 00:03:08,720 Speaker 1: understand how those storms form in the first place, this 49 00:03:08,800 --> 00:03:11,240 Speaker 1: sort of research could allow people to get to safety 50 00:03:11,400 --> 00:03:15,320 Speaker 1: and batten down the proverbial hatches. Continued work by other 51 00:03:15,400 --> 00:03:18,440 Speaker 1: teams has shown that infrasound sensor arrays can detect and 52 00:03:18,480 --> 00:03:25,960 Speaker 1: tracked tornadoes that are over sixty miles or KOs away. 53 00:03:27,919 --> 00:03:30,600 Speaker 1: Today's episode was written by Christopher Hassiotis and produced by 54 00:03:30,639 --> 00:03:32,840 Speaker 1: Tyler Klie. For more on this and lots of other 55 00:03:32,919 --> 00:03:36,080 Speaker 1: sound topics, visit how stuff works dot com. Brain Stuff 56 00:03:36,120 --> 00:03:38,400 Speaker 1: is production of I Heart Radio or more podcasts in 57 00:03:38,440 --> 00:03:41,320 Speaker 1: my heart Radio, visit the I heart Radio app, Apple podcasts, 58 00:03:41,400 --> 00:03:43,160 Speaker 1: or wherever you listen to your favorite shows.