Almost, I was thinking of the Windsor hum. Thanks! More interesting sources in case anyone is interested: [0] https://en.wikipedia.org/wiki/The_Hum https://en

Almost, I was thinking of the Windsor hum. Thanks! More interesting sources in case anyone is interested: [0] https://en.wikipedia.org/wiki/The_Hum https://en.wikipedia.org/wiki/The_Hum [1] https://en.wikipedia.org/wiki/List_of_unexplained_sounds https://en.wikipedia.org/wiki/List_of_unexplained_sounds [2] https://en.wikipedia.org/wiki/Skyquake https://en.wikipedia.org/wiki/Skyquake [3] https://en.wikipedia.org/wiki/Cryoseism https://en.wikipedia.org/wiki/Cryoseism