Even though we can't feel it, the Earth is humming all the time. "If you played it at 10,000 times the speed, you could hear 'white noise' like an old TV set between channels," Fabrice Ardhuin, an oceanographer in France, tells the Huffington Post. Experts discovered the planet's very low vibrations in the late 1990s, and now researchers may be able to explain them, Live Science reports. According to Ardhuin's team, the hum is a result of ocean waves. Waves don't just occur at the ocean's surface, Live Science explains: They can reach to the bottom of the ocean. There, they move along a "bumpy" sea floor, creating pressure that leads to the Earth oscillating, the American Geophysical Union reports.
That could explain the so-called "microseismic" waves behind the hum—at least those lasting from 13 to 300 seconds, according to researchers' models. Shorter microseismic waves could be the result of waves crashing into each other. The wave theory isn't entirely new, Live Science notes, but the findings offer a fuller explanation of what could be happening. "I think (the results are) a relief to the seismologists," says the oceanographer. "Now we know where this ringing comes from, and the next question is: What can we do with it?" One possibility: The research could help experts spot earthquakes occurring a long distance away, AGU notes. (In other recent geological finds, it seems the Earth's core has a core of its own.)