Scordatura

A scordatura (literally Italian for "mistuning"), also called cross-tuning, is an alternative tuning used for the open strings of a string instrument. When used in standard music notation the notes indicated in the score would represent the finger position as if played in regular tuning, while the actual pitch is altered. Use of alternative tunings allows the playing of otherwise impossible note sequences or note combinations or can be used to create unusual timbres. The technique can be described as an extended technique.