It doesn't feel like it was too long ago that I was a child at a beach, utterly fascinated by my mum having told me that if I held a seashell to my ears, I'd hear the ocean in it. You should've seen my face light up the first time I experienced this complete wonder. Which is basically to say that the rushing sound one hears is in fact the noise of the surrounding environment bouncing off and being echoed by the hollow and rounded form of the shell. Turns out, the same effect can be produced with any cavity that sound waves can bounce around in - like an empty cup or even your own hand cupped against the ear!

There you have it. The whole truth and nothing but the truth. It is admittedly not nearly as magical as believing that the seashell roared because it brought along some part of the ocean with it. But I suppose, the way in which the laws of physics work together to make this world seem like a magical place is also nothing less than a marvel too, huh?