Provided herein are acoustic articles (100) that include a porous layer (102) and heterogeneous filler (104) received in the porous layer. The heterogeneous filler is substantially non-porous and present in an amount of from 0.25% to 7% by volume relative to the total volume of the porous layer and has a specific surface area of from 0.01 m2/g to 1 m2/g. The acoustic article has a flow resistance of from 500 MKS Rayls to 12,000 MKS Rayls.