Comprehensive experimental characterization of violin vibration and radiation dynamics

Abstract

Measuring only violin radiation cannot remove ambiguities in resonance peak identification arising from various minor substructure couplings, or whether the radiation arose from the f-holes or surfaces. Measuring only vibrations gives no clue as to how well each mode radiates or even how the vibrational energy was dissipated. To put these into a structural acoustics milieu, comprehensive measurements of all the violin’s energy loss paths were essential. To accomplish this a wide range of calibrated transducers (accelerometers, multiple microphones, near- and far-field microphone arrays, scanning laser vibrometers) were used in a wide range of experiments: cavity mode analysis using interior microphones; interior gas-exchange; EMA on a violin with and without a soundpost; waterfill experiments on a rigid violin-shaped cavity; automated zero-mass-loading, surface-normal (and 3-D) scanning laser EMA on violins supported in a near-zero-damping support fixture; automated far-field radiation measurements over a sphere in an anechoic chamber; bridge tuning effects; near-field acoustical holography over the f -holes. Each technique had limitations, some severe. Some experiments were “table top”; some required expensive associated facilities like an anechoic chamber. Costs of transducers and power-amplifier-control electronics, computer-based acquisition hardware/software varied dramatically; most operational problems occurred in the computer-based data acquisition/analysis systems.