11:13 p.m.: Mysterious noise annoys Anderson couple
Justin Schneider
“Hums,” low-frequency sound phenomena similar to the one experienced by Paul and Sadie Porcaro, have been reported in Taos, N.M., the United Kingdom and New Zealand. In the case of the “Kokomo Hum,” the sound was traced to local industry. But here are some more interesting explanations that have been suggested:
Man-made noise: Low-frequency sounds generated by industry or stereo subwoofers can be amplified by walls and structural geometry
Infrasound: Geological changes and plate tectonics can generate sounds too low to be perceived by the human ear, called infrasound
Pulsed microwaves: Similar to the microwave auditory effect, in which audible clicks are produced by microwave frequencies generated inside the human head
Extremely low-frequency communication systems: Submarines communicate using ELF radio transmissions that may produce other audio effects
Ionospheric heaters: Antennae in Alaska, Puerto Rico, Norway and Russia used to heat the ionosphere create light effects similar to the aurora borealis and may create sound, as well
Tinnitus: A hearing condition that produces ringing or “whooshing” in the ear when no actual sound is present
Tensor tympani: According to a German study, vibration of the tensor tympani, a muscle that tightens the eardrum, may cause a humming effect
— Source: Wikipedia