Interpreting the Input Admittance of Violins and Guitars

The most widespread vibration measurement on musical instrument bodies is of the point mobility at the bridge. Analysis of such measurements is presented, with a view to assessing what range of information could feasibly be extracted from the corpus of data. Analysis approaches include (1) pole-residue extraction; (2) damping trend analysis based on time decay information; (3) statistical estimates based on SEA power-balance and variance theory. Comparative results are shown for some key quantities. Damping trends with frequency are shown to have unexpectedly different forms for violins and for guitars. Linear averaging to estimate the direct field component gives a simple and clear visualisation of any local resonance behaviour near the bridge, such as the bridge hill, and reveals some violins that show a double hill, while viols show only weak hills, and guitars none at all.