Changes of sound absorption capability of wood by organosolv pretreatment

Sound absorption capability and anatomical features of the organosolv pretreated Japanese larch and yellow poplar wood were estimated by stereoscopic observation and two microphone transfer function method. Sound absorption capabilities of organosolv treated wood, in the entire estimated frequency range (50-6,400 Hz), were higher than those of control specimen. Especially, the treated wood's absorption capabilities measured in the frequency range of 2-4 kHz were about two times higher than those of control specimen. By the organosolv pretreatment (at 70-120°C), the weight loss of wood occurred in less than 1% of total weight of wood and the porosity of wood increased slightly. In addition, it was presupposed that microstructural changes of wood occurred during organosolv pretreatment and this structural changes cause the increasing of the sound absorption capability of wood.