VSA Seminar Nov 12, 2021: Jim Woodhouse, Signature modes & formants: comparing stringed instruments

We can learn something interesting by comparing violin family instruments with other stringed instruments: over the centuries, instrument makers have come up with a wide range of different designs. This talk will focus on two aspects of vibration response of instrument bodies: “signature modes”, meaning individual low-frequency modes, and “formants”, meaning features like the violin “bridge hill" involving several modal peaks. Different instruments show a different balance between these ingredients. At one extreme, guitar acoustics seems to be about signature modes, with no formants visible. At the opposite extreme, the banjo is “all formants”: individual modes seem to be rather unimportant. In between, the violin family has both features. Low modes like A0 and B1-/B1+ are important, but the violin also has two formants, while the cello seems to have three. In all instruments featuring formants, they seem to be a major resource for tonal adjustment.