Chladni plate patterns (cymatics) are the nodal patterns traced by loose sand or fine particles resting on a flat plate that is driven into vibration, usually by a bow, speaker, or piezo element touching its edge or center. At certain resonant driving frequencies the plate settles into a standing-wave eigenmode, and the particles are pushed off the rapidly oscillating antinodes and collect along the nodal lines — the curves where vertical displacement stays at zero throughout the cycle. The result is a set of intricate, symmetric line patterns unique to each resonant frequency and plate shape. The German physicist Ernst Chladni first demonstrated this in 1787 by bowing metal plates covered in sand, and the technique became foundational to acoustics, later used by violin and guitar makers to tune the vibrational modes of instrument soundboards and plates.

• Audible range for driving frequencies is roughly 20 Hz–20 kHz; visible sand patterns are typically demoed between about 100 Hz and 1000 Hz.
• Pattern complexity (number of nodal lines/cells) generally increases with driving frequency as higher-order modes are excited.
• Each pattern corresponds to a standing-wave eigenmode of the plate, described by mode numbers (n, m) — analogous to harmonics on a string, but in two dimensions.
• Pattern symmetry depends on plate geometry: square plates tend toward 2- and 4-fold symmetric grids, circular plates toward radial/angular node rings.
• Particles collect at nodes (zero displacement) and are flung away from antinodes (maximum displacement), which is why the sand outlines rather than fills the pattern.
• Used in acoustics research and instrument making (violins, guitars, cymbals) to visualize and tune resonant behavior of plates and soundboards.
• Damping, plate thickness, material stiffness, and boundary clamping all shift which frequencies produce clean, stable patterns.