Some complain that the promise of green energy offered by large wind turbines comes at a cost: a low, rumbling, rhythmic whoosh or groan that travels through the air and earth, sometimes for miles. Furthermore, the earth itself generates a natural, constant hum (though it's typically far below the threshold of human hearing). Scientists believe the hum is created by ocean waves crashing over continental shelves, which creates vibrations that travel throughout the world.
In some cases, the "mysterious sound" videos have been revealed as hoaxes. For example, a college student in Edmonton, Canada, posted a video of mysterious sounds which got nearly 140,000 views on YouTube before she admitted it was fake. She told a local newspaper, "I made the video by taking out my iPhone and merely video recorded my balcony view while holding my laptop right behind it, while my laptop played the Conklin YouTube video in the background. Took less than a minute to do this.... I made the video to show my friends and family how easy it was (literally less than five minutes of my life to make the video and upload it) to make something like that, and how they shouldn't believe everything they see online, and should especially not get fearful."