Heat Ventilation Air Conditioning System (HVAC) is designed to control the environment inside of residential, commercial or industrial buildings by controlling temperature of a room through heating and cooling. However, due to its mechanism, noise is produced in the system and reaches the people inside the building, thus causing distraction, discomfort and uneasiness. There are HVAC silencers in the market; however, the sound absorbing material used is of mineral wool types. In this study, the ducting silencer with the sound absorptive material that made of Arenga Pinnata, Kenaf and composition of these both materials were tested to identify its performance. The experiment was carried out in a testing apparatus that follows the ASTM E477-99 standard. Insertion loss was analysed at the end of the study. From the overall result and comparison, the insertion loss of Kenaf is averagely better than Arenga Pinnata, that is 97.5% higher than Arenga Pinnata. When composition of Arenga Pinnata and Kenaf is used, Kenaf plays important role in sound insertion loss, where when Kenaf composition increase, it increases the sound insertion loss capability.