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 Concerto No. 1 (Paganini) orchestra compared to the solo violin, because the orchestral string section plays less frequently on open strings, with the result that the solo violin part emerges more clearly and brightly from the orchestral accompaniment. Contemporary audiences did not realise that Paganini had retuned his instrument, and were thus all the more amazed at what he appeared able to play. (The more musically adept members of the audience would have recognised the distinctive sound of a violin's open string, and would have observed that this fell on the keynote of work (E-flat), and would have therefore realised that Paganini had re-tuned