Not the first time to be heard, but it’s been heard in multiple places all strangely at the same time.
Unusual and unexplained noises are recorded in various locations around the world from time to time.
While the specific origins of all such sounds may not yet be known, most scientific research points to natural causes such as tidal waves, methane explosions, underground earthquakes, or shifting sand dunes as explanations for these aural phenomena. Although it’s probable that these “weird apocalyptic” booming sounds seemingly coming from the skies have an earthly origin, USGS scientist David Hill says that it’s also possible some of these noises originate from above. (From You Tube description)