The Hum - Wikipedia
https://en.wikipedia.org/wiki/The_HumThe Hum is a name often given to widespread reports of a persistent and invasive low-frequency humming, rumbling, or droning noise not audible to all people. Hums have been reported all over the world; in the United States, United Kingdom, Australia, New Zealand, Canada, India ,Madagascar and Greece and are sometimes named according to the locality where the problem has been particularly publicized, such as the "Taos Hum" in New Mexico and the "WindsorHum" i…