Nabal (instrument)

The nabal is a long, straight brass horn used in Korean traditional music. As the instrument has no valves or finger holes it is not a melodic instrument but rather plays a single sustained tone. The precise frequency of the tone produced can be quite different depending on the size of the individual instrument.

The nabal has historically been used primarily in the military procession music called daechwita, as well as in nongak (rural farmers' music) to signal the beginning and end of performances. Here is the link that shows you how kereans use Nabal.