Making and testing for sound insulation materials from natural fiber composite (Galam wood fiber and polyester matrix) to analyze sound transmission loss and modulus of elasticity. Natural fiber that used is sawdust and wood chips and using polyester as matrix. Wood material chosen due to the availability of abundant so easily obtained and also a waste timber Galam is wasted in the process of building construction. Specimen made in disc shape with 10 cm of diameter and 1 cm thickness. Sound intensity measured in insulated room with sound level meter and speaker as sensor and source and run with variation in frequency of transmitted sound wave. With sound transmission loss theory, sound insulating capability could be analyzed. Measurement of modulus of elasticity is needed to determine deflection capability in loaded condition so it may be a consideration in their application. The result of this research is the best insulation properties is composite with 7% saw dust as filler on 800 Hz sound frequency and the highest value of Elasticity is composite material with 18% wood chip filler.