The steady flow of vehicles is noisy enough as it is, but it also gives off a type of noise the human ear can't hear: seismic noise, or the vibration of the ground. Thus, vibrations given off by cars, trucks, trains, and airplanes on the runway among other modes of transportation haven't really been studied in depth -- until now. A team of researchers from the Scripps Institution of Oceanography have recently found a way to "hear" those vibrations using 5,300 geophones, screwdriver-like devices used to record ground movements. They placed a geophone every 300 feet in Long Beach for their study and soon realized that thanks to the devices, they could count airplanes and measure their acceleration on the runway and even detect larger vehicles like trucks on a highway. In the future, the same method could be used to monitor traffic, which could then lead to better roads and more road signals where they're most needed.
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