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 family have four strings each, are tuned in fifths (except the double bass, which is tuned in fourths), are not fretted and have four rounded bouts while always having a sound post and bass bar inside. In contrast, the viol family instruments usually have five to six strings with a fretted fingerboard, are tuned in fourths and thirds, often have sloping shoulders, and do not necessarily have a sound post or bass bar. The instruments of the violin family are the most used bowed string instruments in the world today. Although all share a place in classical music, they are also