I am learning to play the nyckelharpa, a Swedish folk instrument with a tradition that goes back more than seven centuries. The modern, chromatic nyckelharpa features four played strings and twelve sympathetic strings that resonate and deepen the sound.
The instrument contains a row of wooden keys that contact the strings when pressed, effectively shortening the length of the string and raising (or lowering) the pitch. It is played with a short bow.
The keys (nycklar) produce notes in a fashion similar to pressing a string with one’s finger to the fingerboard of a violin. In the case of a nyckelharpa the keys are located under the strings and the tangents contact the string when each key is pressed. For more information please visit the American Nyckelharpa Association website.