typically the most expensive, followed by leading synthetic core brands, and student steel strings at the lowest price range. Natural gut strings (without the metal windings) are quite inexpensive, especially for the E and A strings. The longevity of strings (all types) is highly variable and influenced by style of play, chemistry of perspiration and its interaction with the string material, presence of fingernails, frequency of play etc. Some players have trouble with certain brands of strings or one particular string from a brand but not with others. The character of the sound produced by the strings can be adjusted quite markedly through the selection of different types of strings. The most noticeable divisions of sound quality for violins is steel, artificial gut ("perlon" core etc.), wound gut, and plain gut. The wound gut tend to have a mellow sound, as do many of the artificial strings, though other artificial core strings are specifically designed to be "bright". Steel and plain gut are both rather bright (full of overtones) but in distinctly different ways: It is possible to tell the difference and yet each is livelier or brighter typically than the wound soft-core and wound-gut strings. Certain styles of music have come to be played with certain types of strings, yet there is no hard and fast rule in this respect as each musician is looking for his or her sound. (Country fiddling is often on steel or all-metal; orchestral and solo is often wound (gut or artificial) with a steel e; baroque or early music may be played rather more than romantic pieces on plain gut.) Some violinists prefer to use little rubber tubes or washers towards the end of the strings which rest on the bridge to protect the bridge and also to dampen the sound. Acoustics It has been known for a long time that the shape, or arching, as well as the thickness of the wood and its physical qualities govern the sound of a violin. The sound and tone of the violin is determined by how the belly and back plates of the violin behave acoustically, according to modes or schemes of movement determined by German physicist Ernst Chladni. Patterns of the nodes (places of no movement) made by sand or glitter sprinkled on the plates with the plate vibrated at certain frequencies are called "Chladni patterns", and are occasionally used by luthiers to verify