The effects of some chemical compounds on the sound absorbing ability of tree bark.

Tree bark is an important natural polymer for sound absorption. The main components in the bark of different tree species are polymers with high molecular weight such as cellulose, hemicellulose, and lignin. The aim of this study is to determine the noise reduction coefficient (NRC), lignin, alcohol-benzene solubility (ABS), carbon (C), and nitrogen (N) contents in samples taken from the bark of different tree species-black locust (Robinia pseudoacacia), narrow-leaved ash (Fraxinus angustifolia), stone pine (Pinus pinea), silver lime (Tilia tomentosa), sweet chestnut (Castanea sativa), sessile oak (Quercus petraea), and maritime pine (Pinus pinaster) and to investigate the relationship between these chemical properties and sound absorption measurements. Tree species showed a statistically significant difference in terms of all measured variables. In the correlation matrix obtained as a result of the analysis, only ABS showed a significant and the highest positive correlation with the NRC, with a correlation coefficient of r = 0.812. ABS in bark is seen as the most important chemical factor regarding sound retention, indicating the abundance of extractives in barks of different tree species. An investigation into the relationship between sound retention and different extractive substance and contents of different extractive substances in bark is recommended for further studies.