Fine tuning of guitar sounds with changed top plate, back plate and rim geometry using a whole body 3D Finite‐Difference model

Abstract

The change of radiated sounds from guitars is investigated in terms of the fine tuning of these sounds applying slight changes to the guitar body, instrument builders would do with their guitars. As changes of these geometries of real guitars can only be perceived when the instrument is put together, the question is mostly open how different the whole instrument would have sounded with slight changes. So here the virtual guitar can be of great use. In the model, the top plate thickness, fan bracing, rim thickness and back plate geometry were changed in a linear way. Then these results could be associated directly to a change in only one geometry parameter. It is not assumed, that the sounds fit one existing guitar perfectly. Rather th overall influence of these changes on the sounds is investigated to show an overall behaviour. As the eigenfrequencies of the guitar body are that many, that a more or less closed resonance curve is achieved (without so‐called 'dead spots'), the changes in the sounds are measured in the following terms: changes in the initial transient of the sounds, its brightness using the spectral centroid, its density using a spectral entropy measurement and amplitude fluctuations of the different sound partials.