The erhu is a two-stringed bowed musical instrument, more specifically a spike fiddle, which may also be called a "southern fiddle", and sometimes known in the Western world as the "Chinese violin" or a "Chinese two-stringed fiddle". It is used as a solo instrument as well as in small ensembles and large orchestras. It is the most popular of the huqin family of traditional bowed string instruments used by various ethnic groups of China. A very versatile instrument, the erhu is used in both traditional and contemporary music arrangements, such as in pop, rock, jazz, etc.
The erhu can be traced back to proto-Mongolic instruments introduced to China more than a thousand years ago. It is believed to have evolved from the xiqin. The xiqin is believed to have originated from the Xi people of Central Asia, and have come to China in the 10th century.
The erhu consists of a long vertical stick-like neck, at the top of which are two large tuning pegs, and at the bottom is a small resonator body (sound box) which is covered with python skin on the front (playing) end. Two strings are attached from the pegs to the base, and a small loop of string (qian jin) placed around the neck and strings acting as a nut pulls the strings towards the skin, holding a small wooden bridge in place.
The erhu has some unusual features. First is that its characteristic sound is produced through the vibration of the python skin by bowing. Second, there is no fingerboard; the player stops the strings by pressing their fingertips onto the strings without the strings touching the neck. Third, the horse hair bow is never separated from the strings (which were formerly of twisted silk but which today are usually made of metal); it passes between them as opposed to over them (the latter being the case with western bowed stringed instruments). Lastly, although there are two strings, they are very close to each other and the player's left hand in effect plays as if on one string. The inside string (nearest to player) is generally tuned to D4 and the outside string to A4, a fifth higher. The maximum range of the instrument is three and a half octaves, from D4 up to A7, before a stopping finger reaches the part of the string in contact with the bow hair. The usual playing range is about two and a half octaves.
Various dense and heavy hardwoods are used in making the erhu. The woods include red sandalwood, rosewood, ebony, purple sandalwood, etc. Particularly fine erhus are often made from pieces of old furniture. A typical erhu measures 81 cm from top to bottom, the length of the bow also being 81 cm.