Customisable sound absorption properties of functionally graded metallic foams

•Functionally graded metallic foam was produced from template replication method.•The sound absorption performances of the graded foam can be customized.•The intersection points for sound absorption curves with two pore sizes can be predicted easily.•Sound absorption performances are changed when thickness proportions of pore sizes are changed.•Sound absorption performances are changed when the foam contains more pore sizes.