Explaining the Fascinating Photographic Trick that Lets You See Sound Waves

NPR just released a fascinating video that does a fantastic job of explaining something called Schlieren Flow Visualization or Schlieren Photography: a photographic trick that allows you to see density changes in air and, therefore, actually capture sound waves on camera.

Starting off with a simple diagram and heat as an example, producer Adam Cole breaks down how this type of photography works, after which he shows you several examples of actual sound waves captured using a high-speed camera and Schlieren Flow Visualization.