Acoustic Guitar Function Model including Symmetric and Asymmetric Plate Modes

The majority of past acoustic guitar models have been limited to guitar surface motion that is characterised by symmetric, low frequency modes. This motion has been modelled as an equivalent oscillating piston. There are acoustically important plate modes that do not behave like a piston, such as the (0,1) plate mode, which do not have symmetric mode shapes. To show the feasibility of extending the frequency range and including asymmetric modes, the lower bout of an acoustic guitar is modelled as an equivalent isotropic circular plate in this paper. The pressure propagation is found using a Rayleigh integral approach that takes into account the spatial motion distribution of the plate. The predictions of this model are compared to experimental measurements made on a folk guitar. This approach also requires fewer empirical inputs to get the guitar body's transfer functions and sound pressure level in comparison to past models.