In this work, the ethyleneâpropyleneâdiene monomer (EPDM) foam was fabricated via 4â4âČâoxobisbenzenesulfonyl hydrazide (OBSH) and phenolic resin (PF) in an effort to prepare the soundâabsorbing composite which has excellent sound absorption at the medium and low frequency. For singleâlayer EPDM foams, cell morphology showed a certain pattern, causing the peak of the sound absorption coefficient move to a higher frequency and the peak value reached a maximum of about 0.75 as the OBSH content increased. In addition, with the foaming temperature increasing, the cell morphology had a different tendency and the peak of the sound absorption coefficient moved first to the higher frequency and then to the lower frequency due to the vulcanization reaction. Compared with the singleâlayer EPDM foams, the sound absorption curve of the doubleâlayer composite made of the singleâlayer EPDM foam and pure EPDM sheet with cavities moved to a lower frequency by about 400âHz. The theoretical calculation method was used to verify the accuracy of the experimental results. This work provided a simple approach to control the sound absorption property of EPDM foamed material and its doubleâlayer composite through from an experimental and theoretical perspective.