Musical tuning to the fundamental note of the unstopped, full string. The strings of a guitar are normally tuned to fourths (excepting the G and B strings in standard tuning, which are tuned to a third), as are the strings of the bass guitar and double bass. Violin, viola, and cello strings are tuned to fifths. However, non-standard tunings (called scordatura) exist to change the sound of the instrument or create other playing options. To tune an instrument, often only one reference pitch is given. This reference is used to tune one string, to which the other strings are tuned in the
Violin technique intervals of perfect fifths by bowing them in pairs. This puts the open strings in just intonation, which means the lower strings may sound flat compared to their nominal equal-tempered equivalents. In practice, this means some compromises must be made, and the strings not always tuned in perfect fifths, particularly on the viola and cello, where the lowest string is the C, three fifths away from the reference A, making the difference more apparent. Small, temporary tuning adjustments can also be made by stretching a string with the hand. A string may be flattened by pulling it above the fingerboard,