Changes in permeability and sound absorption capability of yellow poplar wood by steam explosion treatment

The possibility of improving the air permeability and sound absorption capability of wood by the lowpressure steam explosion of a wood disk was evaluated in this study. By means of comparing control and steam explosion treated specimens, the effects of steam explosion on the appearance, anatomical features, air permeability, and sound absorption capability of yellow poplar (Liriodendron tulipifera) were discussed. The color of steam explosion-treated wood darkened, but significant anatomical changes were not observed by scanning electron microscope (SEM) on the treated sample specimen, as compared with the control. The average air permeability in the fiber direction of treated woods was higher than that of control woods. The sound absorption capability of control and treated yellow poplar was 15% to 50% in the measured frequency range. The sound absorption coefficients of steam explosion-treated specimens were slightly higher than those of normal wood specimens at the high frequency range. These results suggested that yellow poplar is highly sound absorptive in the fiber direction and that the low-pressure steam explosion treatment could be considered a technique for improving the permeability and sound absorption capability of wood in the fiber direction.