Patterns written by sound

Shake a metal plate covered in sand at certain frequencies and mysterious patterns appear. The demonstration, published in 1787 by Ernst Chladni, illustrates a concept known as “fundamental modes of vibration.” Jon Jacobsen, a mathematician at Harvey Mudd College, explains why the experiment still captivates scientists and students today. 

Oh, if you’re wearing a hearing aide - as I was when listening to this - turn it down.