Bow

The bow is probably the most ancient string instrument, dating from human hunter days. One can imagine a bored hunter plucking away at the string of the bow (which was used for hunting), and one day when he put it in his mouth, the sound was louder. Cave paintings dating back as far as 15'000 BCE show this kind of instrument.

The human mouth is typically used as soundbox to make the sound louder. Sometimes a gourd is attached to the bow to function as soundbox.

The San people (or bushmen) of southern Africa still use this instrument. Some other names for this instrument are: Musical Bow, Mouth Bow, Malunga, Pinaka, and Berimbau.

Source: http://searchresearch1.blogspot.com/2012/02/wednesday-search-challenge-21512-is.html

Soundclip

http://searchresearch1.blogspot.com/2012/02/wednesday-search-challenge-21512-is.html