This NPR piece by Adam Cole provides a fascinating new way to view sound and think of it as a spatial, physical phenomenon. This technique, called Schlieren Flow Visualization, has been used to view heat, turbulence, and other changes in air density and energy flow. As an extension, it can be applied to sound as well.
As a deaf person who has always viewed "sound" as a slightly abstract concept, I find this video incredible. What would the world look like if we could see sound resonating around us at all times? If we could access it with our other senses, or translate it into something semi-visible?
Sound, after all, is just another change in air density — a traveling compression wave. A speaker pushes on the surrounding air, creating a wave that travels outward until it encounters the ear drum.