Vibration simulation of guitar top plates from spruce and petung bamboo at subsequent production stages

Abstract

Differences in the construction, material and shape of guitars affect the sound produced, which is related to how the structure vibrates. In this paper, we present a vibration simulation of classical guitar top plates made from spruce and petung bamboo at subsequent stages of production: (i) guitar top plate without sound hole, (ii) guitar top plate with sound hole without bracings, (iii) guitar top plate with sound hole and bracings, and (iv) guitar top plate attached to the body. The change of natural frequencies and mode shapes from one stage to another are presented, as well as the effect of using different top plate materials and bracings. The spruce top plate was found to have lower natural frequencies compared to the petung bamboo guitar at every production stage. The addition of the sound hole does not significantly affect the natural frequencies and mode shapes of both guitar top plates. The addition of bracings, however, significantly alters the natural frequencies and mode shapes of the top plates by introducing more natural frequencies. Top plates with X-bracings tend to have higher frequencies than those with fan bracings. The attachment of the top plate to the guitar body, not yet including the air coupling within the cavity, increases the natural frequencies of the system. These results will be further validated by experimental modal analysis of the guitar top plates.