What Does Sound Look Like?

Just awesome !

NPR provides a way to see sound…

You can actually see sound waves as they travel through the air thanks to a clever photographic trick.

Produced by Adam Cole
Hands shot by Meg Vogel

Schlieren images provided by Mike Hargather (https://infohost.nmt.edu/~mjh/people.html)
Amber Kates
Bobby Gold
J. W. Tang, A. Nicolle and J. Pantelic

Shlieren at Wikipedia :

Schlieren (from German; singular “Schliere”, meaning “streak”) are optical inhomogeneities in transparent material not necessarily visible to the human eye. Schlieren physics developed out of the need to produce high-quality lenses devoid of these inhomogeneities. These inhomogeneities are localized differences in optical path length that cause light deviation. This light deviation can produce localized brightening, darkening, or even color changes in an image, depending on which way the ray deviates.