We investigated the effect of gluing of wood to its acoustic properties. We chose solid spruce wood (Picea abies) and spruce laminated veneer lumber (LVL) with thickness of veneer 0.8, 1.4 and 2.5 mm. LVL was glued with polyvinyl acetate (PVAc) and urea-formaldehyde (UF) adhesives in the test specimens of 400 x 40 x 20 mm. Longitudinal and transverse mechanical excitation of specimens was used, where the frequency response, sound damping, mechanical stiffness and acoustic quality indicators were determined. The number of veneer layers of LVL had a positive impact on the density and stiffness of the material. Higher stiffness was achieved in LVL specimens glued with PVAc adhesive. Bonding adversely affected the speed- and damping of sound in the longitudinal direction of the specimens. Differences between the studied adhesives in this case were not confirmed. Acoustic coefficient K, the acoustic conversion efficiency ACE and the relative acoustic conversion efficiency RACE were significantly lower at the LVL than that of solid wood. These parameters were not significantly different depending on the thickness of the used veneer.
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