Research has been conducted about the absorbtion of sound waves by using silencer glass tube with mixture sample of Shorea sp wood fiber and egg tray. This research using experimental methods to design the impedance tube made of glass with size of 92 cm x 20cm x 20cm. The range of frequencies used in this study was 125Hz, 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz. Samples prepared by carrying out a comparison of wood composition between Shorea sp wood fiber : egg tray : cornstarch like 72%:25%:3% ; 62%:35%:3% ; 50%:47%:3% ; 47%:50%:3% ; 35%:62%:3% ; 25%:72%:3% and with thickness variation of 3mm, 6mm, 9mm. Results showed that the biggest coefficient absorbtion value was 0,9287 on 3mm of thickness and frequencies 1000Hz with composition 25% of Shorea sp wood fiber and 72% of egg tray. The smallest coefficient absorbtion value was 0,1946 on 9mm of thickness and frequencies 125Hz with composition 72% of Shorea sp wood fiber and 25% of egg tray.Keywords : Absorbtion coefficient of sound waves, composition, thickness.
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