“…This force determines the initial excitation and is thus a crucial factor in the composition of the resulting tone. Considerable effort has been devoted to understanding the hammer-string force [1,2,3,4,5,6,7,27,28,29,30,31,32,33]. Hammer felt is a very complicated material [34], and there is no "first principles" expression for the hammerstring force relation F h (y f ).…”