wear, players generally change a string when it no longer plays "true" (with good intonation on the harmonics), losing the desired tone, brilliance and intonation. String longevity depends on string quality and playing intensity. Pitch range A violin is tuned in fifths, in the notes G3, D4, A4, E5. The lowest note of a violin, tuned normally, is G3, or G below middle C (C4). (On rare occasions, the lowest string may be tuned down by as much as a fourth, to D3.) The highest note is less well defined: E7, the E two octaves above the open string (which is tuned to E5) may be considered a practical limit for orchestral violin parts, but it is often possible to play higher, depending on the length of the fingerboard and the skill of the violinist. Yet higher notes (up to C8) can be sounded by stopping the string, reaching the limit of the fingerboard, and/or by using artificial harmonics. Acoustics The arched shape, the thickness of the wood, and its physical qualities govern the sound of a violin. Patterns of the node made by sand or glitter sprinkled on the plates with the plate vibrated at certain frequencies, called Chladni patterns, are occasionally used by luthiers to verify their work before assembling the instrument. Sizes Apart from the standard, full () size, violins are also made in so-called fractional sizes of , , , , , , , and even . These smaller instruments are commonly used by young players, whose fingers are not long enough to reach the correct positions on full-sized instruments. While related in some sense to the dimensions of the instruments, the fractional sizes are not intended to be literal descriptions of relative proportions. For example, a -sized instrument is not three-quarters the length of a full size instrument. The body length (not including the neck) of a full-size, or , violin is , smaller in some 17th-century models. A violin's body length is , and a size is . With the violin's closest family member, the viola, size is specified as body length in inches or centimeters rather than fractional sizes. A full-size viola averages . However, each individual adult will determine which size of viola to use. Occasionally, an adult with a small frame may use a so-called size violin instead of a full-size instrument. Sometimes called a lady's violin, these instruments are slightly