Effect of hydrothermal treatment on the acoustic properties of wood from Walnut and Elm species, utilizable in musical instruments

The objective of this study was to investigate the influence of hydrothermal treatment of walnut (Juglans regia) and caucasian elm (Zelkova Carpinifolia) wood species on their acoustic properties in radial and tangential directions. For this purpose، specimens were prepared with dimensions of 360 (L) ×20 (R) ×20 (T) mm. Heat treatments in water medium were performed at 150ºC for 5 hours. Acoustic properties of specimens (specific modulus of elasticity، damping، acoustical coefficient، acoustical conversion efficiency and wave velocity) measured by free flexural vibration on a free-free bar method. Properties of treated specimens compared with control specimens. Result showed that hydrothermal treatment improved all acoustic properties of specimens. Acoustic properties of radial and tangential surfaces of walnut wood did not show significant difference; while in caucasian elm significant differences obtained between radial and tangential surface properties. Generally، better acoustic properties achieved in tangential direction of heat-treated Caucasian elm species. So، it is recommended as a suitable specimen to be used in making the sound-boards of musical instruments such as Iranian Santour and Xylophones and also resonator boxes.