The chemical modification or impregnation through preparing the wood polymer composites (WPCs) can effectively reduce the hygroscopicity as well as can improve the acoustic properties of wood. On the other hand, a small amount of nanoclay into the chemical mixture can further improve the different properties of the WPCs through the preparation of wood polymer nanocomposites (WPNCs). Kayu Malam wood species with styrene (St), vinyl acetate (VA), and montmorillonite (MMT) nanoclay were used for the preparation of WPNCs. The acoustic properties such as specific dynamic Young’s modulus (Ed/γ), internal friction (Q−1), and acoustic conversion efficiency (ACE) of wood were examined using free-free flexural vibration. It was observed that the chemically impregnated wood composite showed a higher value of Ed/γ than raw wood and the nanoclay-loaded wood nanocomposite showed the highest value. The reverse trend was observed in the case of Q−1. On the other hand, chemical impregnation has a minor effect on ACE of wood for musical instruments. The results suggested that the chemically impregnated Kayu Malam wood polymer nanocomposite (WPNC) is suitable for making soundboards of violin and guitar instruments to be played longer without losing tone quality.