Violin where a stopped note sounds a unison or octave with another (open) string, causing it to resonate sympathetically. Students often use these ringing tones to check the intonation of the stopped note by seeing if it is harmonious with the open string. For example, when playing the stopped pitch "A" on the G string, the violinist could play the open D string at the same time, to check the intonation of the stopped "A". If the "A" is in tune, the "A" and the open D string should produce a harmonious perfect fourth. Violins are tuned in perfect fifths, like
Violin technique other strings are not so equipped. The A string is tuned first to a reference pitch source such as a tuning fork or, in most orchestras, the oboe, typically to 440 Hz, although some orchestras tune to another standard A such as 442, or even as high as 445 or 446 Hz to produce a brighter sound. Early music groups interested in authentic performance may use a lower standard A. When playing with a fixed-pitch instrument such as a piano or accordion, the violinist must tune to accommodate that instrument. The other strings are then tuned to the A in