Effects of surface perforation on the drying characteristics and sound absorption coefficients of Russian poplar board

This study investigated the effects of surface perforation on the drying characteristics and sound absorption coefficients of Russian Simon poplar lumber. The drying process and moisture content (MC) were monitored. The results showed that the perforated wood samples reached 10.9% MC after 14 days, while the control samples reached 11.7% MC after 16 days. The difference in MC between the core and shell of the perforated and control specimens was 1.29% and 2.71%, respectively. The drying stress of perforated wood lumber was tension stress, while compressive stress was observed in control samples. The sound absorption coefficient (SAC) was measured using the transfer function method and two microphone impedance tubes. The results showed that the perforated samples had improved in SAC compared to the control samples, particularly at 1000 Hz. The average SAC of the perforated samples at 1000 Hz was 41% higher than that of the control samples. Furthermore, the noise reduction coefficient (NRC) exhibited a 69% improvement in the perforated samples. Statistical t-test analyses confirmed the significant difference in the SAC of the perforated pieces. Further experiments revealed that the sound absorption performance of perforated samples could be significantly improved by adding air gaps in the back cavity (1, 2, 3 cm), particularly at low frequencies. These findings suggest that perforated poplar boards could be useful for wall building applications when combined with air gaps in the back cavity to enhance sound absorption performance.