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A lump of ice falling down a borehole makes a very satisfying ‘pew’

Of all the sounds we were expecting – and we confess we hadn’t given it a great deal of thought – it definitely wasn’t this one. SOUND UP!

The sound of ice falling down a borehole from r/WTF

PEW!

jizztheory: ‘Reminds me of golden eye for the N64’

Schmich: ‘Ricochet shot in a western.’

And there were some very long and complicated explanations offered for just why it does it. Like this one.

quadrapod: ‘People are relating this to the sound frozen lakes make as they crack but this I’m pretty sure this is just caused by the doppler effect of the falling ice reflecting off the bottom of the borehole.

‘The speed of sound in air is around 343 m/s though it actually goes down a bit the colder it is. The doppler effect causes waves in front of an object to be compressed and waves behind it to be stretched. You can think of it like the object catching up with its own soundwaves in front of it and escaping its soundwaves behind it. If something was moving away from you its pitch would be shifted by a ratio of its velocity and the speed of sound.

‘In other words if you’re traveling at half the speed of sound (~171m/s) then someone behind you would hear sounds you produce as being pitched down by a factor of two and someone in front of you would hear sounds as being pitched up by a factor of two.

‘This also means if someone were standing still while you moved past your pitch would shift from being doubled to being halved, giving the effect that the pitch actually increased by a factor of 4. This effect can actually give a kind of naive understanding of what causes a sonic boom. If something is moving at the speed of sound it’s neither catching up with or outrunning its own soundwaves. Instead the sound waves can be thought of as sort of overlapping on top of each other.

‘Well as the ice falls down the borehole we first hear the doppler pitched down version because its moving away from us. So the whole time we’re hearing a pitched down version and as it falls a waveform of the pitched up version is building up in front of the ice. When it hits the bottom of the borehole that pitched up sound reflects off the bottom and comes back to us resulting in what seems like a strange pew noise. Actually if you looked at both waveforms you could probably get a decent idea of exactly how quickly the ice was falling by comparing their ratios.’

And there was also this one.

UKisBEST: ‘No, it hit a dolphin and the dolphin said ouch in dolphinese.’

Source Reddit u/whywee