Cymatics (from Greek: κῦμα "wave") is the study of visible sound and vibration, a subset of modal phenomena. Typically the surface of a plate, diaphragm, or membrane is vibrated, and regions of maximum and minimum displacement are made visible in a thin coating of particles, paste, or liquid. Different patterns emerge in the excitatory medium depending on the geometry of the plate and the driving frequency.
The apparatus employed can be simple, such as the ancient Chinese spouting bowl, or Chinese singing fountain, in which copper handles are rubbed and cause the copper bottom elements to vibrate. Other examples are a Chladni Plate or advanced such as the CymaScope, a laboratory instrument that makes visible the inherent geometries within sound and music.[clarification needed]
The generic term for this field of science is the study of modal phenomena, retitled Cymatics by Hans Jenny, a Swiss medical doctor and a pioneer in this field. The word Cymatics derives from the Greek 'kuma' meaning 'billow' or 'wave,' to describe the periodic effects that sound and vibration have on matter.
The study of the patterns produced by vibrating bodies has a venerable history. One of the earliest to record that an oscillating body displayed regular patterns was Galileo Galilei. In Dialogue Concerning the Two Chief World Systems (1632), he wrote:
As I was scraping a brass plate with a sharp iron chisel in order to remove some spots from it and was running the chisel rather rapidly over it, I once or twice, during many strokes, heard the plate emit a rather strong and clear whistling sound: on looking at the plate more carefully, I noticed a long row of fine streaks parallel and equidistant from one another. Scraping with the chisel over and over again, I noticed that it was only when the plate emitted this hissing noise that any marks were left upon it; when the scraping was not accompanied by this sibilant note there was not the least trace of such marks.
On July 8, 1680, Robert Hooke was able to see the nodal patterns associated with the modes of vibration of glass plates. Hooke ran a bow along the edge of a glass plate covered with flour, and saw the nodal patterns emerge.
In 1787, Ernst Chladni repeated the work of Robert Hooke and published "Entdeckungen über die Theorie des Klanges" ("Discoveries in the Theory of Sound"). In this book, Chladni describes the patterns seen by placing sand on metal plates which are made to vibrate by stroking the edge of the plate with a bow.
Throughout the 1960s, up until his death in 1972, Swiss medical doctor and Anthroposophist, Hans Jenny took a methodological and exhaustive approach to documenting Cymatic phenomena. He coined the term "Cymatics" in his 1967 book, Kymatik (translated Cymatics). Inspired by systems theory and the work of Ernst Chladni, Jenny delved deeply into the many types of periodic phenomena but especially the visual display of sound. He pioneered the use of laboratory grown piezoelectric crystals, which were quite costly at that time. Hooking them up to amplifiers and frequency generators, the crystals functioned as transducers, converting the frequencies into vibrations that were strong enough to set the steel plates into resonance. He made the resultant nodal fields visible by spreading a fine powder lycopodium spores of a club moss, as well as many other methods and materials. He documented much of his work in still photos which were compiled into two volumes published in 1967 and 1972, and republished in 2001 as a single hardcover edition (see above reference). He also documented his experiments in 16mm films which have since been re-released on a DVD entitled Cymatic SoundScapes: Bringing Matter to Life with Sound. 
Hans Jenny's book influenced Alvin Lucier and, along with Chladni, helped lead to Lucier's composition Queen of the South. Jenny's work was also followed up by Center for Advanced Visual Studies (CAVS) founder György Kepes at MIT. His work in this area included an acoustically vibrated piece of sheet metal in which small holes had been drilled in a grid. Small flames of gas burned through these holes and thermodynamic patterns were made visible by this setup.
Contemporary German photographer, philosopher and Cymatic researcher, Alexander Lauterwasser has brought the work of Hans Jenny into the 21st Century using finely crafted crystal oscillators to resonate steel plates covered with fine sand and also to vibrate small samples of water in Petri dishes. His first book, Water Sound Images,  translated into English in 2006, features imagery of light reflecting off of the surface of water set into motion by sound sources ranging from pure sine waves, to music by Ludwig van Beethoven,Karlheinz Stockhausen, electroacoustic group Kymatik (who often record in surround sound ambisonics), and overtone singing. The resulting photographs of standing wave patterns in both sand on steel plates and standing wave patterns in water, are striking. In this book, Lauterwasser particularly focused on creating exquisitely detailed visual analogues of patterns found in nature, ranging from the distribution of spots on a leopard, to the geometric patterns found in plants and flowers, to the shapes of jellyfish, and most amazingly, the intricate patterns found on the shell of a tortoise.
Composer Stuart Mitchell and his father T.J. Mitchell claim that Rosslyn Chapel's carvings contain references to Cymatics patterns. In 2005 they created a work called The Rosslyn Motet realised by matching Cymatics/Chladni patterns to the 13 geometric symbols carved onto the faces of 213 cubes emanating from 14 arches. The hypothesis that the carvings represent Chladni patterns is not supported by scientific or historical evidence.