Mandolin are used. Usually, courses of 2 adjacent strings are tuned in unison. By far the most common tuning is the same as violin tuning, in scientific pitch notation G–D–A–E, or in Helmholtz pitch notation: g–d′–a′–e″. Note that the numbers of Hz shown above assume a 440 Hz A, standard in most parts of the western world. Some players use an A up to 10 Hz above or below a 440, mainly outside the United States. Other tunings exist, including "cross-tunings", in which the usually doubled string runs are tuned to different pitches. Additionally, guitarists may sometimes tune a mandolin to
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