Provided are acoustic articles having a porous layer (102,104,106) placed in contact with a heterogeneous filler comprising porous carbon and having an average surface area of from 0.1 m2/g to 10,000 m2/g. The acoustic articles can have a flow resistance of from 10 MKS Rayls to 5000 MKS Rayls. Optionally, the porous layer includes a non-woven fibrous layer or a perforated film having a plurality of apertures with an average narrowest diameter of from 30 micrometers to 5000 micrometers. The heterogeneous filler can enhance low frequency performance without significantly compromising high frequency performance, thickness or weight.