Determination of acoustical properties of heat treated laminated wooden panels

This study examines absorption coefficient values of laminated panels made of heat treated wooden materials and determines the effect of heat treatment on absorption coefficient value of laminated wooden wooden panels. For this aim, woods of scotch pine (Pinus sylvestris L.), Uludağ abies (Abies bommulleriana Mattf.), iroko (Chlorophora excelsa) and 18 mm thickness of MDF in conformity with the TS 64-5 EN 622-5.Wooden contra-laminated panels were obtained as non heat treated and heat treated panels by adhering non heat treated and heat treated (2 hours at 185 oC) scotch pine and iroko on the face layers, non heat treated Uludağ abies on the middle layer with double component Polyvinyl acetate (PVAc-D4) adhesive. Some physical and mechanical properties of these panels and MDF were determined. Absorption coefficient values of the panels were determined according to TS EN ISO 354 in two different surface types as flat surface and perforated in two different assembly types as E 70 (air spaced) and E 70+ (rock wool filled).As a consequence; it was determined that heat treatment declines the physical and mechanical properties of the wooden laminated panels in determinate rates, however increases the absorption coefficient values of the wooden laminated panels. Effect of heat treatment on absorption coefficient varies according to surface features and assembly types of panels and frequency, the highest increase was obtained in flat surface, air spaced E 70 assembly type and in 1000 Hz with a rate of 60%. The highest absorption coefficient values were obtained in 160 Hz in flat surface panels while in 500 Hz in perforated panels.Even though heat treated wooden panels have low mechanical properties; improvement in physical properties as dimensional stabilization and sound absorption coefficient value extends the area of usage in heat treated panels. Its use may be recommended as an acoustic design material in theatres, opera halls, conference and meeting halls, indoor swimming pools, sports centers and outdoor spaces.