Which instrument, with a range of around 3 octaves, has its lowest string tuned to C below middle C, with the others to G, D and A?
Viola partly because of its larger size: the notes are spread out farther along the fingerboard and often require different fingerings. The viola's less responsive strings and the heavier bow warrant a somewhat different bowing technique, and a violist has to lean more intensely on the strings. The viola's four strings are normally tuned in fifths: the lowest string is C (an octave below middle C), with G, D and A above it. This tuning is exactly one fifth below the violin, so that they have three strings in common—G, D, and A—and is one octave above the cello. Each string
Octobass at the Musical Instrument Museum in Phoenix, which uses modern wound metal strings, is tuned C, G, D. This tuning gives it a low range two octaves below the cello and one octave below the modern double bass with low C extension. Berlioz specifically noted this tuning in his orchestration treatise, but considered it erroneous. As on the Paris instrument, the mechanism allows each string to cover a perfect fifth, giving it a high range to A. The fundamental frequencies of the lowest notes in this tuning lie below 20 Hz — the commonly-stated lower bound of human hearing range