The spatial inhomogeneity of pressure inside a violin at main air resonance
Guy Vandegrift, Eccles Wall · The Journal of the Acoustical Society of America · 1997
The fluctuating pressure inside a violin is investigated at the A0 (main air) resonance, under the assumption that the walls are kept rigid. Three effects are shown to contribute to a reduction in the fluctuating pressure near the violin’s f-holes. The strongest effect arises from a tendency to form a standing wave within the relatively long, thin shape of the upper bout. A second and smaller effect arises from the violin’s nonuniform shape, and is modeled by treating the upper bout as an acoustical waveguide with nonuniform cross section. A third effect is associated with the Green’s function of an acoustical radiator, and will significantly reduce the fluctuating pressure in the immediate vicinity of the violin’s f-hole. Experimental verification of the theory is obtained by measuring the fluctuating pressure inside a rectangular box, with the resonance being driven by a small loudspeaker located outside the aperture.