Electrophonic sound
Electrophonic sound is a hiss or crackle heard at the same moment a bright fireball is seen, caused by radio waves.
Sound travels at about a third of a kilometre per second, so a sonic boom from a fireball 50 kilometres away arrives minutes after the flash. Yet for centuries, witnesses have reported hissing, crackling or popping sounds heard at the very same moment as the fireball. These are called electrophonic sounds.
For a long time scientists doubted them, because ordinary sound could not travel so fast. A leading explanation now is that very bright fireballs give off radio waves, or rapid flickers of light, which reach the observer instantly. These can make nearby objects such as hair, glasses, dry leaves or wire fences vibrate slightly and produce faint audible sounds.
Laboratory experiments in 2017 showed that light flickering at audio frequencies can make some materials emit sound. Not everyone hears electrophonic sounds, and they are rare. If you hear one, write down exactly what it was like, where you were and what was near you.
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