cymatics
Cymatics is the study of visible sound and vibration, examining how acoustic energy can organize matter on surfaces or within media into characteristic geometric patterns. In typical demonstrations a plate or membrane is driven at a chosen frequency while powder, salt, sand, or a viscous liquid sits on its surface; as the boundary conditions and frequency change, material accumulates along nodal lines and other features reveal the plate’s vibrational modes. Modern imaging can also show patterns in fluids or gels inside transparent media.
Historically, patterns formed by vibrating plates were observed by the 18th‑century German physicist Ernst Florens Friedrich
Applications range from physics education and acoustical engineering to art and design; cymatic demonstrations are used