Sound Absorption Rate and Sound Transmission Loss of CLT Wall Panels Composed of Larch Square Timber Core and Plywood Cross Band

Abstract

The square timbers of larch having cross section of $90mm{\times}90mm$ were glued laterally to be formed $1,200mm{\times}2,400mm$ panels which were used as cores for CLT wall panels. Then, structural plywood panels having size of $1,200mm{\times}2,400mm$ were used as cross band covering the small square timber cores to manufacture CLT wall panels. The sound absorption rate of CLT wall panels and polyester board attached CLT wall panels were investigated. The mean sound absorption coefficients of the former and the latter in the frequency range of 100-6400 Hz were 0.21 and 0.74, respectively. The noise reduction coefficients (NRC) of those were 0.21 and 0.40, respectively. Also, the mean sound transmission loss of CLT wood panel in the frequency range of 50-1600 Hz was 45.12 dB and that value at the frequency of 500 Hz was 42.49 dB. It was suggested that the polyester board attached CLT wall panels could be used as housing wall because of its high sound absorption rate and high sound transmission loss.

Fig. 1. Specimens for sound absorption rate measurement (left, CLT; light, polyester board).

Fig. 2. Sound absorption estimation apparatus.

Fig. 3. Impedance tube for measuring sound transmission loss (Left, photograph; Right, schematic diagram).

Fig. 4. Sound absorption rate of CLT wall panels (Graph legend values denote specimen numbers).

Fig. 5. Sound absorption rate of polyester board attached CLT wall panels (Graph legend values denote specimen numbers).

Fig. 6. Sound transmission loss of CLT wall panels (Graph legend values denote specimen numbers).