Kalimantan has abundant natural resources, including wood. The physical properties of wood have varying strength and flexibility and could replace concrete reinforcement steel. In this study, the mechanical properties and sound insulation of one of Kalimantan's natural fiber combined with polyester matrix were investigated. Natural fibers used were teak wood (Tectona Grandis) with sawdust and wood chips. Specimens were made using the hand lay-up method with a wood volume fraction variable of 25%, 35%, and 50%. Afterward, the bending, morphology, and sound insulation tests were carried out. In this study, it can be concluded that the higher wood volume fraction used, the higher the ability of sound insulation. Conversely, it reduces the modulus of elasticity. Besides, the form of sawdust fillers has a better ability than wood chip fillers in terms of sound insulation and the modulus of elasticity.