Biopolymer foam was prepared based on vegetable oil and Polyol Flexible  with commercial Polymethane Polyphenyl Isocyanate (Modified Polymeric-MDI) with different proportion ratio. This is to determine the acoustic property based on the influence of biomonomer (M) proportion ratio with processable flexible polyol (E). The acoustic property of biopolymer foam was examined by using an impedance tube test according to ASTM E-1050 of sound absorption coefficient (α). Based on the result obtained, the highest ratio of biomonomer to absorb sound is greater than processable flexible polyol namely as M₁₀₀ and E₁₀₀ respectively. The morphology study revealed that M₁₀₀ foam have lower cell sizes compared to other proportion ratio of M with E foams. The smallest averaged cell size is 871 µm was obtained from M₁₀₀ with sound absorption coefficent (α) of 0.996 at 3796 Hz frequency level. As the conclusion, M its self gives highest α than the combination of both polyol as well as E which gives almost the same results as M but at lowest frequency level.