This is mind blowing!
German physicist Heinrich Rubens became a living legend in 1905 when he invented a tube that uses fire to visualize sound waves. When there's no sound in the tube, the flames rise to the same height. But, when a sound is added, the wave affects the amount of gas that is fed through each hole and causes different flame heights to be visible.
Derek Muller from Veritasium traveled to Denmark to check out an updated version of the Rubens tube. The physicists and chemists here have developed an device with 2,500 holes in the top. The difference is that these holes are not all in a line like a traditional Rubens tube, but actually cover a plane. "The Pyro Board"
The results are pretty amazing. Check it out: