Eigenmodes and quality of violins
Jesús Alonso Moral, Erik V. Janssen · The Journal of the Acoustical Society of America · 1982
From a Scandinavian violinmakers' competition, a number of 24 violins of different qualities were selected. Input admittances as function of frequency were recorded perpendicularly to the top plate at two positions on top of the bridge. The admittance curves at the side of the bass bar show three resonances at approximately 400, 500, and 700 Hz and a broad resonance around 3 kHz. Three “acoustical” quality criteria were extracted from these curves: (1) the average level of the three resonance peaks (high is favorable), (2) the summed discrepancies between single peak levels and the average level (small is favorable), and (3) steepness of upwards slope from 1500 to 3000 Hz (steep is favorable). The levels of input admittances of the bass bar and sound post sides are approximately the same. A fourth acoustical quality criterion was extracted from the two curves: (4) the level discrepancies between the two curves (small is favorable). Calculated “acoustical” quality points correlate well with given tonal quality ratings (a correlation coefficient of 0.92 with five violins with singular faults excluded).