This is a Ruben's tube, an invention from 1905 that visually demonstrates the correlation between sound waves and the pressure they create. https://t.co/2KCgGFYP0z https://video.twimg.com/ext_tw_video/1779021623909052416/pu/vid/avc1/658x452/-T8yH50qzAstmW8v.mp4?tag=17