Why can sand be arranged into beautiful projects?

Kran, a German scientist, honored as the father of classical acoustics, once had a passion for studying stringed instruments’ pronunciation principles. To explore the violin’s law of vibration, he did a series of interesting experiments, from the simplest square plate onwards. Take a square, flat sheet of metal, secure in the middle, and sprinkle a layer of fine sand evenly on it. He used his finger to press one or two points on one side of the metal plate, while the other used a violin that had been rubbed from the top of the rosewood resin from top to bottom on the adjacent edge, causing the metal to vibrate. Each time you finish rubbing, remove the violin from the metal plate immediately and then continue to rub the same part of the sheet until it makes a noise. Then soften friction to maintain the sound of the sheet. You can then observe that sand grains on the flat metal sheet bounce, gradually grouping, forming a beautiful pattern called the Kran project. The part and number of fingers against different flat metal plates, the blueprints that sand forms are also different. Besides, each type of project is related to a particular type of tone. Experiments using circular, triangular, and pentagon metal plates may also yield similar results.

The Kran project is a symbolic drawing of the stationary wave. The grains of sand on a flat metal plate always gather at the eyes (buttons) of non-vibrating waves. These eyes are caused by many points connecting to the wave line, which is also the project’s wavy line. For square or circular metal plates, these ripples’ shape and location can be used to calculate mathematically accurately. But with instruments like violin, gong, cymbal, bell, etc. No longer is a simple two-dimensional flat metal plate. Their musical properties are determined by size and shape and related to many other factors such as raw materials, processing technology, etc., which can only be determined through experimentation. Making a high-quality microphone requires superior craftsmanship.
Since ancient times, people use their ears to hear sounds. And now sound can manifest thanks to the grains of sand. It is very miraculous. No wonder exposing a variety of projects on flat metal plates, Napoleon inspired: “I have” seen “the sound of it.”