I'm surprised nobody mentioned radio communication. The AM (Amplitude Modulation) transmission is even quite simple to understand and build. You can even create an electric arc between the ground and the transmitting tower as a cheap (and dangerous) receiver: [this video]
AM radio demodulated by an arc at a transmitter tower.
I'm not entirely sure what process is converting to sound, but the metal fence makes a great antenna and we are talking about 10's of feet from the antenna with 500 kW AM at 200 kHz going into it. It could actually have been arcing: [this video]
[this video] [link] Do not understand the explanation. Just put a space will get the hn act. And copy is just right click or touch-hold. Am I missing something ?
I grew up in a house that was next door to a radio rebroadcasting facility, and we could definitely hear the radio station coming from the walls of our house sometimes, e.g. even their station identification so there was no ambiguity. I assumed it was the house wiring (mostly knob and tube) acting as an antenna. I'm reasonably sure that was AM, though. Was the sound you heard like either of these? [this video] [link]
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