The effect of wood removal on bridge frequencies

Finite element analysis methods have been used to calculate the effects of trimming bridges on the first several frequencies of vibration. Violin bridges and both standard and Belgian designs of cello bridges have been investigated. Calculations of both in-plane and out-of-plane vibrating modes have been made when the feet were rigidly fixed. In one case, no motion out-of-plane was permitted. In the other, only the string locations were restricted to in-plane motions. The analysis confirms and expands the previous concepts of bridge action. The density of modes above the fundamental mode appears to explain the action of the bridge in absorbing substantial amounts of energy at all frequencies above that of the lowest mode. The effects of trimming in different locations are different enough so that it would be possible for a violin maker to adjust individual frequencies.