David R. Peterson
Math. Dept., Central Arkansas Univ., Conway, AR 72035
A unique characteristic of the hammered dulcimer is that the middle bridge splits string courses into a length ratio of 3:2, so the two string segments have an interval of a musical fifth. When the longer segment is struck, coupling through the bridge to the shorter segment causes every third harmonic to have two modes of vibration with slightly different frequencies, which interact to produce vibrations with slowly varying amplitudes, which are determined by bridge impedance, decay rates, and slight tuning differences. A theoretical model has been developed, which applies to any number of strings tuned to rational multiples. The distinct sound of the hammered dulcimer depends upon the initial transient, which is strongly influenced by the hardness of the hammer and the strike position.