Source: http://en.wikipedia.org/wiki/File:Erhu.png
The Chinese (erhu or erh-hu) is a kind of 2-string violin. One side of the soundbox is usually covered with vellum (often python skin), while the strings are not pressed against the thin stick-like neck. The playing technique is similar to that of playing a guitar string by gently touching it to create a 5th harmonic. The hairs of the bow are inserted between the two strings, which means that the bow cannot be sepatared form the instrument. The bow thus vibrates the two strings simultaneously. All these variations create the instrument's unique sound.
Source: http://en.wikipedia.org/wiki/File:Erhu.png
Source: http://en.wikipedia.org/wiki/Erhu
Video clip by 馬向華 MA Xiang-Hua:
http://www.youtube.com/watch?v=re6LVYisnYY