Eerie sci-fi pinging comes from frozen lake, see the cause
Sunday, December 9, 2018, 4:11 PM - Here's one to put on your to-do list for winter: find a frozen lake and surprise your friends with this creepy cool sound effect.
The weird pinging sound -- as you hear in the video above -- would seem at home in a science fiction blockbuster, but the explanation is decidedly more down-to-earth. While the surface of the lake is frozen over, the water underneath isn't. When the rock hits the surface of the ice, it makes the sheet vibrate up and down, kind of like a giant drum.
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The strange echoing effect arises from the difference between the speed of sound waves through air, water, and ice; the sound traveling through the ice reaches us about 10 times faster than the sound traveling through the air.
HEAR IT: ICE ECHO ACROSS A FROZEN LAKE
If you're feeling really ambitious when it comes to your outdoor experiments, you might want to try several different lakes. You'll get different sounds from different types of ice. "Clear" ice -- the glassy-looking sheet that forms in cold, still conditions with no snow -- produces the highest-pitch noise. That's because the sound waves are free to travel through the pure ice without impediment. Cloudier opaque ice, which forms when snow falls on the lake surface and freezes, produces a lower tone, as the ice's grainier structure disrupts some of the sound.