đàn đáy

From the Encyclopedia of Vietnamese Music at PBwiki.

Đàn đáy is a three-stringed lute with a roughly rectangular body and a uniquely long neck. The upper half of the neck plays no major role in performance except to lengthen the string, giving it a characteristic sound, while the lower half is fretted and is the region used by the player. As with most lutes, the player plucks with the right using either a plectrum or fingers, and presses the string between the frets, which are high like many other Vietnamese instruments for pitch-bending. The instrument is almost used exclusively in the context of ca trù, a northern Vietnamese traditional chamber genre.