Acoustic properties of glued laminated bamboo and spruce-pine-fir

Noise pollution has become a worldwide issue, which has a negative effect on human health. The sound reduction index and absorption coefficient of glued laminated bamboo (glubam) and spruce-pine-fir (SPF) were firstly measured in this study by using the impedance tube method. The effect of moisture content on the acoustic performance of these materials was also investigated. Experimental results revealed that for thick-strip glubam and SPF, the higher moisture content, the higher sound reduction index but lower sound absorption coefficient. However, moisture content does not have an obvious effect on acoustic properties of thin-strip glubam. By comparing with other materials, it can be found that glubam and SPF have relatively high normal-incidence transmission loss but low absorption coefficient and noise reduction coefficient. Glubam shows the similar but even better acoustic insulation performance than SPF, which confirms the possibility of using glubam as an alternative of wood materials. Moreover, a finite element model was built up to simulate the measurement of sound transmission loss in an impedance tube. Some parametric studies were then conducted using the finite element model to prove the effectiveness of increasing thickness, using composites and double-layer panels on improving the soundproof performance of materials.