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
Scientific pitch Pyke Hullah in the mid-19th century, but never established as a standard. In the 19th century, Italian composer Giuseppe Verdi tried to stop the increase in pitch to which orchestras were tuned. In 1874 he wrote his "Requiem" using the official French standard "diapason normal" pitch of A4 tuned to 435 Hz. Later, he indicated that 432 Hz would be slightly better for orchestras. One solution he proposed was scientific pitch. He had little success. In 1988, Lyndon LaRouche's Schiller Institute initiated a campaign to establish scientific pitch as the classical music concert pitch standard. The Institute called this pitch