Improvement of acoustic properties of Maple and Beech by hydrothermal treatment

  Acoustic property as one of the special characteristics of wood is widely used in making musical instruments. Thus examining acoustic property of wood and factors affecting its improvement is of vital importance. Furthermore, modifying the characteristics of wood with environmentally friendly methods has become increasingly important recently. In the current study, two wood species native to north of Iran that is Beech (Fagus orientalis L.) and Maple (Acer velutinum) were examined in terms of their acoustic properties. Samples were also treated under hydrothermal treatment. The effects of hydrothermal treatment on acoustic properties of samples were measured with free-free flexural vibration method. In order to examine the acoustic properties of two wood species of Beech and Maple, samples in the dimensions of 360 (longitudinal) × 20 (radial) × 20 (tangential) mm were cut according to ISO 3129 standard. Hydrothermal treatment at 150 ° C for 5 hours was applied on samples. Acoustic properties of the treated samples such as modulus of elasticity, damping of vibration, wave velocity, quality of sound, acoustical coefficient and acoustical conversion efficiency were evaluated in two directions of Longitudinal-Radial and Longitudinal-Tangential. Acoustic properties were compared with control samples. The results of this study showed that hydrothermal treatment of wood has a significant effect on improving the evaluated acoustic properties except for the modulus of elasticity and acoustical coefficient factor in comparision with control samples. In general, the greatest effect was observed on mortality hydrothermal treatment of wood, the quality of sound, and acoustical conversion efficiency in species of Maple. The results also indicated that there was no significant difference between the acoustic properties in two directions of Longitudinal-Radial and Longitudinal-Tangential in the treated samples. The effect of hydrothermal treatment on improving acoustic properties of the samples could be due to the withdrawal of water soluble extractives in samples with cleaning material accumulated in vessel ducts, fiber and other stractural elements of wood, as well as increased dimensional stability during treatment in treated samples. According to the results of this study, the hydrothermal treatment of wood species, especially Maple species can be used in manufacturing sound-boards as well as resonator boxes of musical instruments such as Xylophones, Violin, and the Iranian Santour.
Keywords: Hydrothermal treatment, Acoustic properties, Musical instruments, Flexural vibration, Extractives.
Keywords: Hydrothermal treatment, Acoustic properties, Musical instruments, Flexural vibration, Extractives.
Keywords: Hydrothermal treatment, Acoustic properties, Musical instruments, Flexural vibration, Extractives