What Does Sound Look Like?

NPR have produced this short video to demonstrate a clever photographic trick which enables you to actually see sound waves. The technique, invented in the mid-nineteenth century by German physicist August Toepler, is called Schlieren Flow Visualization. It enables scientists and engineers to see things that are normally invisible. Watch the video below for a full explanation of how the technique works and to see sound waves made by clapping, a towel snapping, an AK-47 firing and more.