The use of natural fibres has the potential to replace the role of synthetic fibres as a composite material. Rice husk ash and bagasse are natural fibres that are abundant in nature. These fibres have the potential to be used as sound-absorbing composites. This research was conducted to determine the potential of the composite of rice husk ash and bagasse with sticky rice flour as a sound-absorbing acoustic panel. The variation in composite thickness is 20 mm and 25 mm. The composite was then given a resonator with a variation of the resonator thickness of 3 mm and 6 mm and a variation of the resonator cavity of 4 mm, 6 mm, and 8 mm. Testing of this composite specimen is based on standard ASTM E1050-98 testing using a two-microphone impedance tube. The test results showed that the highest decibel drop value was obtained from a combination of 25 mm composite thickness, 6 mm skin resonator thickness, and 8 mm cavity skin resonator with an average decibel drop value of 4.55 dB.