Mysterious Stratospheric Sounds Detected by Solar-Powered Balloons

Solar-powered balloons are recording mysterious sounds in the stratosphere, including the sound of distant thunderstorms, falling meteors, or turbulence. The balloons listen to the Earth from a dozen miles up, recording in infrasound, below the human hearing range. The sounds captured include the ocean waves, earthquakes, wind turbines, and a mysterious crackling that scientists can't identify yet. The world of infrasound is vast and largely unmapped, and almost every flight picks up unidentified sounds. Anyone can fly an eavesdropping balloon, and the more eyes in the sky, the more we learn.