I'm going through one of my intermittent Hammered Dulcimer Dreaming phases right now, largely on account of the playing of the ever youthful Esmail Vasseghi from the Clemencic Consort which has enchanted me now for 35 years or more:

http://www.youtube.com/watch?v=ozMFw1EOid8

Esmail plays the santur, which has the strings divided into two parts, so each string gives two notes, which is the same principle as the instrument in the waulking song video, only there the instrument looks like one of Harry Partch's cast offs!