Acoustical properties of petung bamboo for the top plate of guitars

Abstract

Abstract In this paper, the use of petung bamboo (Dendrocalamus asper) as an alternative material for the top plate of acoustic guitars was evaluated. In the first research stage, the analysis was carried out on petung bamboo splits, which were treated with three different preservation conditions, namely unpreserved, preserved by boiling in water and preserved by boiling in a solution of 5% borax and boric acid. The vibration damping ratios and the sound radiation coefficients of these three types of splits were measured. It was found that their vibration damping ratios were not significantly different, whereas the sound radiation coefficient of the petung bamboo splits preserved in borax and boric acid was 40–60% higher than the other two variants. Based on this result, in the second research stage, three acoustic guitars with top plates from the borax–boric acid preserved petung bamboo, spruce, and pine were constructed. The top plate frequency response function of the three guitars was evaluated. Here, the spruce guitar was used as a reference for the generally preferred guitar sound characteristics, whereas the pine guitar was included as a sample of guitar made from local Indonesian wood. The results showed that the frequency response function of the petung bamboo guitar were generally five times lower than that of the spruce guitar, but two times higher than that of the pine guitar. The response amplitudes of the bamboo guitar were significantly higher than those of the spruce and pine guitars for frequencies between 200 and 400 Hz. Based on the results, it is concluded that petung bamboo has the potential to be applied as an alternative material for guitar top plates. However, since the bamboo guitars exhibits different resonances, the produced sound will have distinctive characteristics compared to the sound from guitars with spruce top plates.